Powerloop plays at the end of a level, after you've completed it.
Wakeup Nights plays when your game is over.
These are all songs that sound exactly the same as when you are playing the game. If you pop this CD in your PC, it'll show the songs as soundtracks in the list, just as it does when you pop in the CD for Wipeout.
You can tell when the music is midi, or from the CD, when you play the game.