[__tsidewinder__]

Well, a lick is a small musical phrase, usually with only single notes. I'm sure different people will give you different definitions. A riff is also a musical phrase, but its usually made up of chords. Maybe riff could be defined as a small part of a chord progression, I really don't know. I think again, different people will give you different definitions, because lick and riff are slang words, at least to my knowledge.

A bridge is usually a part in the middle of the song that moves away from the chorus and verse. It can be described as a transition, and is sometimes described as the "middle eight" or the interlude. I can garuntee there are many people on this forum who can describe this better than me, and I really hope someone does! I can't garuntee the accuracy of all this. If you want more accurate info, just head to your favourite search engine and type "definition of Riff" or "definition of lick" etc. And see what you get.


"edit"

Well, someone beat me to the punch. Listen to him before me.
I hope this helps a bit.