AS you learn about the UK political system. 2 sides of the course and 4 units in each. You learn about the Judiciary, the Constitution (pros, cons, whether it needs to be changed etc.), learn about the political parties, differences between political ideologies, pressure groups, Parliament (HoC, HoL advantages and disadvantages of each), the Prime Minister, and loads more I can't remember.
A2 your school/college chooses what you study. We're doing the US; so are covering US political history, the US Constitution, President, Elections, Lobby groups etc etc.