whats the difference between mk1 series 1 and 2s?

i know the rear panel and bumpers are, what else, cheers, just being curious

Take a look at the home page, there's loads of articles on it.

A car is a Series 1 if it has an alphabet "A" as the third letter in the VIN. Whereas a car with the breakpoint with later dash and large rear lights is Series 2.