The term filibuster is somewhat uncertain, they can be considered as small-scale pirates with an area of action restricted to the shores of the Caribbean Sea where they attacked populations and ships of the same size.
“The expedition to Panama has never been overcome […] only the cruelty and rapacity of the victors, buccaneers and filibusters stained their brightness, troop recruited without pay, of little discipline and uncontrolled, but stimulated in their atrocities by Morgan himself”
Their boats were small as 44ft. The buccaneers also called themselves filibusters, possibly because of the type of vessel used by English-speaking Fly-boats that were light and low-draft boats.
Some renowned Filibuster are:
A privateer, like the corsairs, was a pirate with papers. As its name indicates, the privateer were privately financed individuals to carry out piracy. These pirates sailed on privately owned armed ships, robbing merchant ships and looting settlements belonging to a supposedly rival country of the financier's nationality. The most famous of all corsairs or privateers is the Englishman Francis Drake, who made a fortune pillaging Spanish settlements in the Americas after Elizabeth I granted him a privateer's commission in 1572.
The use of privateer allowed states to project sea power beyond the capabilities of their regular navies, but there were trade-offs. Because privateering was generally a more lucrative occupation than military service, it tended to divert manpower and resources from regular navies.
Private management could be a shady business, and this explains some of the lexical overlap with the word pirate. Privateers sometimes went beyond their commissions, attacking vessels that did not belong to the target country. This extracurricular raiding and looting was not distinguished from piracy as defined above. At other times, outlaw pirates operated with the tacit encouragement of a government but without the privateers' written legal authorization. In historical settings where these practices were common, the line between privateer and pirate was blurred.