"+Ralf Haring I think it really comes down to easing people into new paradigms. It's funny that collections use folder icons but act just like labels. So, it's really the label paradigm disguised as folders and given a different name entirely.
Personally, I think they went with the more generic "collections" name so that if/when other services were rolled into it, we wouldn't end up with similar but conflicting/confusing names. For instance, when you have a bunch of emails grouped together, it's known as a label (from Gmail). However, when you have a bunch of videos grouped together, it's a playlist. When you have a bunch of songs or photos grouped together, it's an album. When you have a bunch of miscellaneous files grouped together, it's a folder. Everyone has been dealing with these different names for grouping different types of media together, and "collections" is a new term that could apply to all of these.
Perhaps it will become more obvious once Google Drive is finally released."