i'm at work too...haha...
first off...awesome avatar
there's so many different ways to structure point sparring and so many ways to structure contact sparring that you can really get technical with the explaination. that said, i can put it in three VERY general catagories.
1. light to no contact point sparring: where you can either make very light contact to score a point to a vital area (many tournament judges will disqualify you for excessive use of force so to speak if you are too rough).
2. full contact point sparring/old school blood and guts sparring: pretty much full contact, and you can blast away at each other but will be stopped when a point is scored.
3. all out full contact sparring: pretty much like boxing or kickboxing here. you just keep on pounding away at each other until one gives up, is knocked out, or the round is over.
these are just my ways of generalizing contact and point sparring...ask me tomorrow and maybe i'll have a different definition or catagory for you. but between this answer and the ones already given or that will be given i think you'll get the general idea.