[kohse]

Image is a company. Like DC Comics, Marvel, or Dark Horse.
Prestige is a format. It is also sometimes called "Bookshelf" format meaning that there is text on the binding that can be seen if its in a bookshelf. These can be special one shots or collected editions or trade paperbacks.
A one shot is just that. One shot one issue end of story. It may or may not take place in the continuity of other books. DC has a cool idea called "Elseworlds". If you see the logo on a DC book it means that that book is not in the same timeline as the regular comics.
Collected editions and trade paperbacks are the same thing pretty much. they are collections of multiple issues of regular comics or mini-series' that are combined into one larger book.

Multiple covers are just the same book with a different cover. If they are made by Dynamic Forces they are usually aimed at the collector but sometimes companies will put out variant covers just for the hell of it. My company, BloodFire Studios, prints what we call "Tour Editions". These are limited print run books that we release as the books are finished. When all the books in a story line are complete, we will release them with different covers through normal distribution channels. We sell these to raise money for the larger print runs and they are only available from us directly from our website or while we are on tour (hence the name Tour edition).

[sacrelicious]

Whoa, did you just dis Superman? No fucking way...

[ToastyKen]

I just started getting into graphic novels myself, and I don't know much about the mainstream comics scene...

Anything by Will Eisner, take A Contract with God for a start.. it's considered to be the first "graphic novel". (He coined the term.) It's basically a collection of 4 short stories about people living in 30s/40s New York tenements.

The Watchmen, written by Alan Moore. It's a departure from your typical superhero stuff that's more realistic and quite interesting.

[ToastyKen]

I'd like to add that your best bet for a book on the details of the comic form (and a little bit of ahistory) is Understanding Comics by Scott McCloud. It's written in the form of a comic itself, as well. Truly excellent book. I HIGHLY recommend it!