I dont' know about between the 2 models you mentioned, but I recently replaced the screen on my Mid 2013 Air with the display from a Mid 2012 Air.
what worked:
Screen mounts and display cord plugged in straight away, absolutely no issues.
what didn't work:
the FaceTime camera in the Mid-2012 used a different connector. Also, the camera plugs into the I/O board on the Mid-2012 model. the 2013 model uses a camera with a differernt connector that plugs directly into the logic board. I tried to get around this by using the logic board also from the Mid-2012 model, but it wouldn't boot.
Second, the wifi/bt card in the Mid-2012 is about half an inch shorter than in the newer model, meaning that the antenna cables will not reach the connections on the newer card.