What are all the differences between the "2023 M3" iMac models and the "2021 M1" iMac models replaced?

The "2021 M1" and "2023 M3" iMac models all have been discontinued. However, this Q&A has been updated subsequently and remains quite useful for anyone considering any of these models on the used market.

There are two "2021 M1" iMac models -- the iMac "M1" 8-CPU/7 GPU/2 Ports 24" (2021) and iMac "M1" 8 CPU/8 GPU/4 Ports 24" (2021) -- and two "2023 M3" iMac models -- the iMac "M3" 8 CPU/8 GPU/2 Ports 24" (2023) and iMac "M3" 8 CPU/10 GPU/4 Ports 24" (2023) -- that replaced their predecessors.

With even a detailed inspection of these iMac models, it would be difficult to tell them apart, but there are some notable differences. The short answer is that the later iMac models have significantly faster processors/graphics processors as well as more advanced wireless connectivity and the option of more RAM if configured accordingly at the time of purchase. They have different identifiers, too.

It also is worthwhile to understand the similarities, as well. Although some readers may already be satisfied with this quick answer, a detailed analysis still can be useful.

Photo Credit: Apple, Inc. (iMac 2021 M1/2023 M3 Models)

External Differences

For all practical purposes, the "2021 M1" and "2023 M3" iMac models are externally identical, but there are differences shared across lines by the entry-level and higher-end configurations, respectively.

All of these models use a wafer thin, all aluminum design with flat sides and a light gray frame around the display and a small "chin" underneath. By default, these iMac models are mounted on an aluminum stand and are not VESA compliant, but all can be configured with a VESA mount option instead of the stand at the time of purchase at no extra charge.

Despite the marketing as "24-Inch" 4.5K Retina displays, all of these iMac models actually have a 23.5-Inch LED-backlit widescreen TFT active matrix "Retina 4.5K" display with a native resolution of 4480x2520 at 218 ppi with "support for 1 billion colors," True Tone technology, wide color (P3), and brightness of 500 nits.

All of these iMac models also have a good quality 1080p FaceTime HD camera, three-mic array, and six-speaker system for video conferencing.

Connectivity is the major point of external differentiation between the entry-level and higher-end models in each series. All have a 3.5-mm headphone jack conveniently located on the left side of the display, but the entry-level models -- the iMac "M1" 8-CPU/7 GPU/2 Ports 24" (2021) and iMac "M3" 8 CPU/8 GPU/2 Ports 24" (2023) -- have two USB-C shaped Thunderbolt / USB 4 ports whereas the higher-end models -- the iMac "M1" 8 CPU/8 GPU/4 Ports 24" (2021) and iMac "M3" 8 CPU/10 GPU/4 Ports 24" (2023) -- have four USB-C shaped ports, but two of the ports support Thunderbolt 4 / USB 4 and the other two support the slower USB 3 standard.

The higher-end models from each line also were bundled with a power supply that includes a Gigabit Ethernet port whereas the entry-level models lack a Gigabit Ethernet port by default, but either could be custom configured with the same power supply as the higher-end models at the time of initial system purchase for an extra US$30.

Color Differences

The "2021 M1" and "2023 M3" iMac models share the same seven color options -- blue, green, pink, silver, yellow, orange, and purple. The colors are dark on the back and sides of each system and a lighter shade of the same color on the front below the light gray bezel that wraps around the display.

Photo Credit: Apple, Inc. (iMac 2021 M1/2023 M3 Color Options)

However, not all models were offered in all colors. The entry-level model in both lines only was available in blue, green, pink, and silver, whereas the higher-end model from both lines was offered in the same colors as the entry-level model in addition to yellow, orange, and purple.

Included Accessory Differences

The "2021 M1" and "2023 M3" iMac models were bundled with the same color-matched input accessories, with differences between the entry-level and higher-end models from each line.

By default, all models shipped with a wireless "Magic Mouse" with multi-touch surface support, but the entry-level models have a small aluminum wireless "Magic Keyboard" (A2450, EMC 3619) without "Touch ID" or a numeric keypad. The higher-end models have a small aluminum wireless "Magic Keyboard with Touch ID" (A2449, EMC 3579), but it still lacks a numeric keypad.

Photo Credit: Apple, Inc. (Magic Keyboard with Touch ID and Numeric Keypad)

At the time of system purchase, the entry-level models could be custom configured with the same "Touch ID" equipped keyboard as their higher-end siblings for an extra US$50. Either model could be custom configured with a "Magic Keyboard with Touch ID and Numeric Keypad" (A2520, EMC 3957) for an additional US$80 for the entry-level models and an additional US$30 for the higher-end models.

Any of these models additionally could be custom configured at the time of purchase to swap out the Magic Mouse for a Magic Trackpad (which provides multi-touch input and Force Touch support) for an extra US$50 or both a Magic Mouse and a Magic Trackpad for an additional US$129.

Identification Differences

The "2021 M1" and "2023 M3" iMac models are practically impossible to tell apart without specific identification details. As the site has done for more than two decades now, EveryMac.com has hand documented these identifiers from the hardware itself.

Model Numbers commonly are shared by multiple models and are not ideal for long-term identification, accordingly. However, the Model Numbers for the "2021 M1" iMac and "2023 M3" iMac models actually are unique.

Nevertheless, other identifiers commonly are better for more specific identification. In software, the Model Identifier is sufficiently unique for just about all purposes. The EMC Number also tends to be more specific than the Model Number as it always is less likely to be shared by future models using the same case type. However, like the Model Number, it is inconveniently located on the underside of the stand for the "2021 M1" models and buried in software for the "2023 M3" models.

These identifiers for all of these iMac models are as follows:

24" iMac	Subfamily	Model	EMC	Model ID
"M1" 7-Core GPU	M1 2021	A2439	3664	iMac21,2
"M1" 8-Core GPU	M1 2021	A2438	3663	iMac21,1
"M3" 8-Core GPU	M3 2023	A2874	8207	Mac15,4
"M3" 10-Core GPU	M3 2023	A2873	8206	Mac15,5

Additionally, EveryMac.com's Ultimate Mac Lookup feature can uniquely identify all of these iMac models by other identifiers, as well.

Internal Differences

The "2021 M1" and "2023 M3" iMac models share many parts, but the later models have faster, more modern processors/graphics processors as well as more advanced wireless connectivity.

The "2021 M1" iMac models are powered by a 3.2 GHz Apple M1 processor (SoC) with eight cores (4 performance cores, 4 efficiency cores). The entry-level model has a 7-core GPU and the higher-end model has an 8-core GPU. They also are equipped with 802.11ax wireless and Bluetooth 5.0.

The "2023 M3" iMac models, on the other hand, are powered by a 4.05 GHz Apple M3 processor, albeit one also with 8 cores (4 performance cores and 4 efficiency cores). The entry-level model has an 8-core GPU and the higher-end model has a 10-Core GPU. They are equipped with faster, newer Wi-Fi 6E (802.11ax) wireless and Bluetooth 5.3, also.

In practice, benchmarks show that the "2023 M3" models are about 35% faster in single core tasks and 40% faster in multicore tasks; a significant speed boost compared to their predecessors.

All of these models have "unified" onboard memory and SSD storage that cannot be upgraded at all after the initial system purchase. At the time of system purchase, though, the "2021 M1" iMac models could be upgraded to 16 GB of RAM whereas the "2023 M3" iMac models could be upgraded to 16 GB or 24 GB of RAM.

"2021 M1" & "2023 M3" iMac Comparison Charts

The major differences between the "2021 M1" and "2023 M3" iMac models -- processors/graphics processors, connectivity, memory options, and more -- are summarized below:

Entry-Level Models

	2021 7 GPU	2023 2 8 GPU
Architecture:	Apple M1	Apple M3
Processor Cores:	8 Cores	8 Cores
Graphics Cores:	7 Cores	8 Cores
Thunderbolt:	2 (USB-C)	2 (USB-C)
USB 3:	None	None
Gigabit Ethernet:	None*	None*
Color Options:	Blue Green Pink Silver	Blue Green Pink Silver
Std. Keyboard:	No Touch ID	No Touch ID
Std. RAM:	8 GB	8 GB
Max. RAM:	16 GB**	24 GB**
Std. Storage:	256 GB	256 GB
Max Storage:	2 TB†	2 TB†
Wi-Fi:	802.11ax	Wi-Fi 6 (802.11ax)
Bluetooth:	5.0	5.3
Model Number:	A2439	A2874
Model ID:	iMac21,2	Mac15,4
EMC Number:	3664	8207
Original Price (US):	US$1299	US$1299
Original Price (CA):	C$1599	C$1699
Original Price (UK):	£1249	£1399
Original Price (AU):	A$1899	A$2199
Original Price (SG):	S$1849	S$1899

Higher-End Models

	2021 8 GPU	2023 10 GPU
Architecture:	Apple M1	Apple M3
Processor Cores:	8 Cores	8 Cores
Graphics Cores:	8 Cores	10 Cores
Thunderbolt:	2 (USB-C)	2 (USB-C)
USB 3:	2 (USB-C)	2 (USB-C)
Gigabit Ethernet:	Yes	Yes
Color Options:	Blue Green Pink Silver Yellow Orange Purple	Blue Green Pink Silver Yellow Orange Purple
Std. Keyboard:	Touch ID	Touch ID
Std. RAM:	8 GB	8 GB
Max. RAM:	16 GB**	24 GB**
Std. Storage:	256 GB, 512 GB	256 GB, 512 GB
Max Storage:	2 TB†	2 TB†
Wi-Fi:	802.11ax	Wi-Fi 6 (802.11ax)
Bluetooth:	5.0	5.3
Model Number:	A2438	A2873
EMC Number:	3663	8206
Model ID:	iMac21,1	Mac15,5
Original Price (US):	US$1499, US$1699	US$1499, US$1699
Original Price (CA):	C$1849, C$2099	C$1949, C$2199
Original Price (UK):	£1449, £1649	£1599, £1799
Original Price (AU):	A$2199, A$2499	A$2499, A$2799
Original Price (SG):	S$2149, S$2449	S$2199, S$2499

* Gigabit Ethernet is provided via the power supply. The entry-level models could be custom configured to include the same Gigabit-equipped power supply as the higher-end models for an extra US$30.

** At the time of purchase, either model could be custom configured to include 16 GB of RAM for an extra US$200. "2023 M3" models also could be custom configured with 24 GB of RAM for an extra US$400. RAM cannot be upgraded subsequently.

† Both models can, or could, be custom configured with up to 2 TB of storage at the time of system purchase at additional cost. Storage cannot be upgraded subsequently.

Ultimately, the "2023 M3" iMac models are a relatively modest "speed bump" update compared to their predecessors, but with 35%-40% more overall performance, more graphics processors, more advanced wireless connectivity, and the option of additional RAM at the time of purchase, are an improvement.

New & Used iMac Purchase Options

There are many places to purchase a new or used iMac. However, buying from a quality company with a solid track record in the Mac game will provide the best experience and save you money and time, too.

In the US, site sponsor Adorama sells new iMac models with free shipping. Other World Computing sells used and refurb iMac models at bargain prices with free shipping, as well. Finally, if you need to sell an iMac, A+ BBB-rated Cash for Your Mac will buy your older iMac with an instant quote and prompt payment.

In the UK, site sponsor Hoxton Macs sells used iMac models with a one-year warranty and free next day delivery throughout the UK. Delivery across Europe also is available starting at just £9.99 for two-day delivery to France and Germany.