a formal indication of a choice between two or more candidates or courses of action, expressed typically through a ballot or a show of hands or by voice.
Typically a vote doesn't require any anything beyond an indication of your choice, whereas a rating usually accompanies a review. See my argument in that thread why it's a rating and not a vote and therefore why a review is required.
Note that reviews are not fundamentally required; it's an admin option.
That said, rating does seem more accurate so I've changed that. Though interestingly, I did see that the microformat we use actually calls them votes too (http://www.data-vocabulary.org/Review-aggregate/).