What are all the differences between the "2021 M1" iMac and the "2019" iMac it replaced? Is there any reason to still consider an older model?

The "2019" and "2021 M1" 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 three "2019" 21.5-Inch iMac models -- the iMac "Core i3" 3.6 21.5" 4K, "Core i5" 3.0 21.5" 4K, and "Core i7" 3.2 21.5" 4K -- and two "2021 M1" iMac 24-Inch models -- the iMac "M1" 8-Core CPU/7-Core GPU 24" 4.5K and iMac "M1" 8-Core CPU/8-Core GPU 24" 4.5K.

With even the quickest of glances at these systems, some differences are immediately apparent, but there are much more substantial differences that are not obvious. Accordingly, a detailed comparison can be particularly useful.

Photo Credit: Apple, Inc. (iMac 2019 21.5" & iMac 2021 M1 24")

External Differences

The "2019" and "2021 M1" iMac models use all aluminum cases with the display mounted atop a stand. However, the "2019" iMac models only use silver colored cases and bulge at the back and sharply taper to a 5 mm edge at the sides of the display. The "2021 M1" iMac models, by contrast, are offered in seven colors and are uniformly thin with flat sides.

The "2019" iMac models have a black frame around the edge of the display to maximize contrast whereas the "2021 M1" iMac models have a light gray frame around the display, a design decision that some online critics particularly dislike.

The "2019" iMac models have a 21.5" 4096x2304 "Retina 4K" display whereas the "2021 M1" iMac models -- despite being only slightly larger physically -- manage to pack a significantly larger 23.5" 4480x2520 "Retina 4.5K" display.

Finally, the "2019" iMac models have a 720p webcam, speakers integrated at the bottom edge of the display, and dual microphones. The "2021 M1" iMac models go a step further with a better quality 1080p webcam, a three-mic array, and a six-speaker system.

Connectivity Differences

The earlier "2019" iMac models have more connectivity options than the later "2021 M1" iMac line.

The "2019" iMacs have an SDXC-capable SD card slot, four USB 3.0 ports, two Thunderbolt 3 (USB-C) ports, one Gigabit Ethernet port (10/100/1000Base-T), and one 3.5 mm headphone jack. These models can support one 5120x2880 (5K) external display at 60 Hz and also are equipped with 802.11ac Wi-Fi and Bluetooth 4.2.

The entry-level "2021 M1" iMac only has two USB-C shaped Thunderbolt / USB 4 ports and a 3.5 mm headphone jack. The higher-end "2021 M1" iMac also has two USB 3 ports with a USB-C connector and Gigabit Ethernet by default on its power supply. These models can support a larger 6016x3384 (6K) external display at 60 Hz and have faster 802.11ax Wi-Fi and Bluetooth 5.0, though.

Identification Differences

There is no mistaking the "2019" and "2021 M1" iMac lines when they are side-by-side, but many other models look similar, so specific identifiers are necessary for precise identification. As we have done for more than two decades now, EveryMac.com has hand documented these identifers from the hardware itself. You're welcome.

In software, the Model Identifier is sufficiently unique for just about all purposes. Externally, the EMC Number is best as it is less likely shared by other models, although it is inconveniently located on the underside of the stand.

These identifiers for the "2019" and "2021 M1" iMac models are as follows:

iMac Model	Subfamily	Model ID	EMC No.
"Core i3" 3.6 21.5"	2019, 4K	iMac19,2	3195
"Core i5" 3.0 21.5"	2019, 4K	iMac19,2	3195
"Core i7" 3.2 21.5"	2019, 4K	iMac19,2	3195
"M1" 7-Core GPU	M1 2021	iMac21,2	3664
"M1" 8-Core CPU	M1 2021	iMac21,1	3663

Additionally, EveryMac.com's Ultimate Mac Lookup feature also can uniquely identify each of these iMac models by their serial numbers.

Internal Differences

Internally, the "2019" and "2021 M1" iMac models have little in common. They use different architectures, graphics, memory, and storage.

The "2019" iMac models use Intel's eighth-generation "Coffee Lake" architecture with four or six core processors, dedicated Radeon Pro graphics, and RAM and storage that can be upgraded after system purchase. RAM can be upgraded to as much as 32 GB at any time.

The "2021 M1" iMac models, by contrast, use Apple's own M1 architecture with an 8-core processor and a "unified" graphics processor, memory, and storage. The "2021 M1" iMac can have its RAM upgraded to 16 GB at the time of purchase for an extra US$200, but it cannot be upgraded as substantially as its predecessor or at all after initial system purchase. For all practical purposes, the "2021 M1" iMac models are sealed and disposable.

21.5-Inch "2019" & 24-Inch "2021 M1" iMac Comparison Chart

The major differences between the 21.5" iMac "2019" and 24" iMac "2021 M1" models -- design, displays, connectivity, processors, upgrades, and more -- are summarized below:

	2019 21.5" (i3)	2019 21.5"	2021 M1 24"
Architecture:	Intel Coffee Lake	Intel Coffee Lake	Apple M1
Generation:	8th	8th	1st
Processor Type:	Core i3*	Core i5*	M1
Processor Speed:	3.6 GHz*	3.0 GHz*	3.2 GHz
Processor Cores:	4	6	8
Std. RAM:	8 GB	8 GB	8 GB
Max. RAM:	32 GB	32 GB	16 GB**
RAM Type (DDR4):	2400 MHz	2666 MHz	Unified
RAM Upgrade:	Yes	Yes	No
Std. Storage:	Hard Drive♦	Fusion Drive♦	Unified
SSD Connector:	No/Yes†	Yes†	No
Video System:	Radeon Pro 555X	Radeon Pro 560X††	Unified
Video Type:	GDDR5	GDDR5	Unified
Video Memory:	2 GB	4 GB	Unified
Display Size:	21.5-Inch	21.5-Inch	23.5-Inch
Native Res:	4096x2304	4096x2304	4480x2520
Second Display:	5K	5K	6K
eGPU Support:	Yes	Yes	No
Webcam:	720p	720p	1080p
SD Card:	Yes	Yes	No
Gigabit Ethernet:	Yes	Yes	No/Yes‡
Wi-Fi:	802.11ac	802.11ac	802.11ax
Case Color:	Silver	Silver	7 Colors
Apple Model ID:	iMac19,2	iMac19,2	iMac21,2 iMac21,1
EMC Number:	3195	3195	3664/3663
Original Price (US):	US$1299	US$1499	US$1299 US$1499 US$1699
Original Price (CA):	C$1699	C$1949	C$1599 C$1849 C$2099
Original Price (UK):	£1249	£1449	£1249 £1449 £1649
Original Price (AU):	A$1999	A$2299	A$1899 A$2199 A$2499

* By custom configuration, the iMac "Core i3" 3.6 21.5" 4K and "Core i5" 3.0 21.5" 4K could be equipped with a six core 3.2 GHz Core i7 (I7-8700) processor for an extra US$300 or US$200, respectively. EveryMac.com also has documented this custom configuration as its own model.

** At the time of purchase, either model could be upgraded to include 16 GB of RAM for an extra US$200. RAM cannot be upgraded subsequently.

♦ Later models shipped by default with SSDs.

† If the 21.5-Inch models were not configured with a "Fusion" Drive or SSD at the time of purchase, the PCIe connector for the SSD is not onboard and a second drive cannot be installed later. If they were configured with a "Fusion" Drive or SSD, this connector is onboard and occupied by the SSD. All models have at least one internal storage drive that can be upgraded, though.

†† By custom configuration, the stock iMac "Core i5" 3.0 21.5" could be equipped with an AMD Radeon Pro Vega 20 with 4 GB of dedicated HBM2 video memory for an extra US$350.

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

So, is there any reason to still consider an older "2019" iMac over a newer "2021 M1" iMac?

Ignoring subsequent iMac models and only considering these two, in some respects, the "2021 M1" iMac objectively represents a "one step forward, one step backwards" kind of progress compared to the "2019" iMac that it replaced. Most notably, the "2021 M1" iMac is (1) significantly faster, (2) has a bigger, better display, (3) has a better webcam and audio, (4) has faster Wi-Fi (802.11ax), and (5) supports a larger second display (6K). These are clear advantages and most users, who do not care about buying an essentially disposable product, likely should prefer the "2021 M1" iMac.

However, particularly given lower discount prices on the used market, the older "2019" iMac models remain well worth considering. The "2019" iMac models provide (1) a well-tested architecture, (2) arguably better physical connectivity with at least two more USB 3 (USB-A) ports and an SD card slot, (3) upgradable RAM, (4) upgradable internal storage, (5) eGPU support, and (6) the ability to boot Windows. For some users, one or more of these advantages are enough to prefer an older iMac instead.

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.