The most recent MacBook Airs use M3 chips – and there is a M4 chip in some iPad Pros now.
The M1 MacBook Airs were only available in the 13" size. The M2 and M3 MacBook Airs were available in both 13" and 15" sizes (although the 15" M2 MacBook Airs are discontinued now.)
M1 MacBook Airs lack a MagSafe 3 charging port.
You can custom-order 24 GB of RAM on M2 and M3 MacBook Airs. That wasn't an option on the M1 models.
M3 MacBook Airs can drive two external displays (with limitations) when their lids are closed. The limit for the M1 and M2 models is one external display, whether the lid is open or closed.