A straw poll is a vote that is not binding on a group of people. For example, up until this year, Iowa Republicans had conducted a straw poll in presidential primary years. People would get together and vote, but that vote had no legal meaning. It just gave a sense as to who had support in Iowa at that point in the race.
A tracking poll is a poll that is administered many times over a given period. By administering the same poll over and over again, pollsters can see if attitudes towards candidates or issues are changing over time.
A benchmark poll is done once at the beginning of a campaign. It measures attitudes towards the candidate and towards various issues at that time. It gives candidates information that they need to start their campaign strategies.
An exit poll is conducted after people vote. It asks people how they voted as they leave their polling place.
A push poll is a poll that asks questions not to actually get answers but to push people to have a certain opinion about a candidate. For example, a push poll might ask “would you be more or less likely to vote for Hillary Clinton if you were told that she had illegally kept classified emails on a private server?” This is not really meant to gather information but rather to change voters’ opinions about a candidate.