What's the difference between the two?
Garageband is prettier - Soundtrack costs money? - that's about as far as i know. I've already got soundtrack which came with FCP4.
What are the main differences between the two, technically?
I really couldn't tell you technically the difference. I would say, however, that there is a fundamental difference. Soundtrack only allows you to manipulate loops whereas GarageBand lets you record audio and MIDI and manipulate those inputs. I reccomend that you watch the latest keynote.
