I just noticed that on the JQuery website they state:

"JQuery is a new kind of JavaScript Library"

but on the Mootools site it says:

"Mootools: A compact JavaScript Framework"


I was always of the belief that JQuery and Mootools were competing versions of the same thing (whether that be a Library or Framework). So one of them must be incorrect.

In this case, it's two words for pretty much the same thing. The difference may be that Mootools extends native objects, which creates a different JavaScript environment in which to operate, while jQuery does not extend purely native objects, as everything is chained to the one global object that it creates, which is jQuery. It does sometimes extend native objects that are connected to the jQuery chain, but this does not affect the ordinary global namespace, only the jQuery one. So this is a main difference between those two systems, though I wouldn't say it necessarily makes one a framework and the other a library, as this seems to me more a choice of semantics.