Buccaneers were a kind of privateers or free sailors particularly to the Caribbean Sea during the 17th and 18th centuries. First established on northern Hispaniola as early as 1625, their heyday was from the Restoration in 1660 until about 1688, during a time when governments were not strong enough and did not consistently attempt to suppress them.
Corsair is a word generally used to describe either Muslim or French such as The Barbary pirates, Muslims who terrorized the Mediterranean from the 14th until the 19th centuries, the name implied that they did not attack Muslim ships and many times sold captured prisoners as slaves.
Pirate is generally a term to imply either men or women that attack ships or coastal towns to plunder or capture prisoners for ransom. Theft, kidnapping, and murder all apply to the role of a pirate, in the case that water and a boat are involved. Pirates do not discriminate against places or victims and all is fair game.
A privateer is a private person or ship that engages in maritime warfare under a commission of war. Since robbery under arms was a common aspect of seaborne trade until the early 19th century all merchant ships carried arms. A sovereign or delegated authority issued commissions, also referred to as a letter of marque, during wartime.