Hub sizes?

A friend of mine had one of the late 80's shape 100's which used four hole mags on a 14inch rim, my mid 90's 100 (500se) uses five hole mags on a 15inch rim. Not sure on the 80 or 90 models though it would not surprise me if the hub changed on those too?

It's quite possible that there's a number of differences to do with the bolt pattern and most likely the offset.

As an example old A3 wheels do not fit the new A3 and vice versa.

You can buy hub adaptors which you bolt to the hub and then fix your wheels to, but these aren't available for every car and is dependent on the offset of the wheel as to whether you can get away with what is effectively a spacer as well.