Early and late fighters

[bolox]

Are you referring to the RAF Squadron types?
If so what it really breaks down to is early has 2 sections of upto 6 AC in each. Late has 3 sections of upto 4 AC and can use finger 4 and diamond formations, which are not available to early squadrons.
All formations apply to whole Squadron.

Can't say if there's any difference in AI behaviour between the 2 (I haven't noticed anything obvious.)