whats the diff between the WRX, and WRX TR?

I like my saabaru but do wish I had the 4-pot brakes. For some reason, I’m thinking the rims, the '06 9-2x didn’t come with the upgraded brakes but still has the 2.5L 4. The STi drivetrain is a major difference like dozr stated, for that reason alone your better off. They want a lot of money for the upgraded diff’s.