What's the difference between "drivel" and "nonsense"?
Drivel is a type of nonsense: it's generally spoken, usually at length, and it's probably deadly boring. It's different from "babble" in that the person saying it is at least trying to pretend it makes sense, but this is hardly a redeeming feature.
Nonsense, on the other hand, can be written as well as spoken, and it doesn't have to be long or boring. For example, answering "yes" to a question such as "What's your favorite [X]" is nonsensical without being drivel.