The upvote/downvote poll lets the audience submit their responses then up and downvote all other audience submissions. Its the easiest way to form a an audience consensous on the top questions or issues they'd like to address.
This is the only poll type where the audience will be able to see other participants' responses on the response page. Each respondent will be able to submit an upvote or a downvote on all of the responses received on the poll. Upvotes and downvotes do not count against the polls response limit.
It is important to note here that upvote downvote polls do not allow for voting functionality when used within a survey. Voting can only be facilitated when this poll type is activated invdividually to ensure that all participants have the opportunity to vote on all of the submitted responses.