please help me what each pedal does.. and terms like "boost" "compress" and also difference of boost from distortion

Please HELP!
here:
http://www.uberproaudio.com/who-plays-what/332-paramore-josh-farro-guitar-gear-rig-and-equipment


http://www.youtube.com/watch?v=qZtYtUXHzyc - in here they said its boost but it sounded just like distorted?