Difference between a primary and a caucus

A primary is a state-level election where party members vote to choose a candidate affiliated with their political party. Party candidates selected in a primary then run against each other in a general election. Thirty-four U.S. states conduct primary elections.

A caucus is a local meeting where registered members of a political party in a city, town or county gather to vote for their preferred party candidate and conduct other party business. Caucuses typically are used in combination with a state convention to elect delegates to the national nominating convention for presidential elections.