[AndyEssex1]

Most of the main differences have already been made but I can think of a few that might either put someone off Idol, or maybe they will prefer it:

The contestants can use instruments and most are very talented musically so they can play a variety.
The show seems to focus 99% on the contestants and 1% on the judges which is the opposite in the X Factor
America has an enormous country and western following (because once you get out of the cities like New York and Miami thats all they listen to) so expect a hell of a lot of that (I don't mind a little bit, but not too much please).
The auditions are done in private, which I still like.
The host, Ryan Seacrest is very cheesy and a typical American, as is the whole show (ie completely over the top and full of promotions for Ford and Coke)
The guest mentors are very good. This year we had GaGa, Cheryl Crow, Miley Cyrus, Usher to name but a few.
Jimmy Iovine from Innerscope records is the main show mentor and he is fantastic. He is the man that signed GaGa when everyone else turned her down. He also has always let her do her own thing.