What I have come to believe is that, this is the most prominent feature that distinguishes Dojo from ExtJS. This provides the opportunity to change the look and feel of Dojo based apps more easily as compared to ExtJS. The look and feel of ExtJS can be very easily noticed.
I am still at a pretty early stages of learning and so might have a wrong notion, but I would definitely appreciate if you could suggest as to what makes ExtJS framework different from Dojo Framework?
Also, I keep stumbling on these terminologies of Framework and Libraries, could you also clarify, when are they Framework and when are they Library or do both mean the same?