The 13-inch MacBook Pro wasn't redesigned when it gained the M2 processor, and the latest iFixit teardown shows exactly how little did change.
iFixit found the 13-inch MacBook Pro with M2 nearly identical to the M1 model
At a glance, the external casing is identical down to the printed model number on the bottom. However, the EMC number is different, which is the only way to tell the two machines apart from the outside.
Once inside, iFixit was able to point out a few differences in the logic board and heat sink. The heat sink has slightly rounded corners in the M1 model, while the M2 has squared-off corners.
The M2 board was able to fit into the M1 case, but it wasn't able to boot properly since the device couldn't detect the internal peripherals. That means you cannot perform a logic board swap on an older model just to get the M2, at least not without bringing your own mouse and keyboard. Touch ID was also disabled in this Frankenstein machine.
The lack of upgradeability between generations appears to be limited by a firmware lock, since the hardware itself seems interchangeable. It isn't clear if this was a deliberate limitation on Apple's part, but given previous behavior by the company, it seems likely.
The SSD read and write speeds that reviewers are commenting on were also addressed by the iFixit teardown. As we discussed in our review, the M1 MacBook Pro has two 128GB flash chips for the 256GB capacity versus the M2 having one 256GB flash chip. There's more parallelization in the M1 MacBook Pro at 256 GB than there is in the M2 MacBook Pro with the same capacity, and therefore, more speed.
When AppleInsider did a comparison between the two machines, we had a difficult time telling them apart. The M1's performance is still good, and the lack of physical differences made them indistinguishable.
The 13-inch MacBook Pro with M2 is available to purchase, but it sits at an odd place in Apple's lineup. The M2 MacBook Air will launch in July, and that is expected to be a much more exciting machine for consumers.