Sail the Caribbean in search of fame and fortune
There are several different types of ships in Pirates and they're mix and match between different eras. That's because the terminology is a bit complicated and obscure. Even the name "ship" meant a specific type of ship in those days (a three masted, square rigged vessel) but today a ship is just about anything that floats that isn't a boat or a canoe.
The earliest buccaneers and the early pirates would have used single-masted ships called sloops, but they're different from what we call a sloop today - and there's another sort of sloop used by the navy (called a "ship sloop" at the time). For Pirates it's the ship sloop that gets called a Sloop. It's a small warship, often used for hunting pirates. It's a very good ship if you're planning on a spot of piracy yourself.
The tradition of pirate stories is for pirates to use schooners, so that's the smallest ship type in Pirates. Schooners are rigged with fore-and-aft sails, which means they sail close to the wind. That's important, as you can escape from bigger ships with square-rigged sails by sailing to windward (bigger ships are faster with the wind behind them, going to leeward).
Note: Sailing ships don't just go in the direction the wind blows (to leeward). They can actually sail in the opposite direction to the wind (to windward) and a schooner can go within about 45 degrees of the direction of the wind. Ships work their way to windward by sailing close to the wind on one side before tacking and going close to the wind on the other side, zig-zagging up-wind a bit at a time.
A Snow is a slow two-masted vessel that would normally be used for trading. It's designed to carry a fair amount of cargo while being easy to handle with a small crew.
What we call a Barque is a larger three-masted vessel. This is the classic sailing ship. In later centuries with better ship-building techniques and new materials they became a lot bigger and could have a lot more masts and sails.
A Brigantine is a two-masted vessel with a mixed rig (some square sails, some fore and aft) used either for trade or in naval service with a fairly heavy gun armament.
A true warship that you don't want to tangle with is a Frigate which has a single gun deck and is built for speed. You're not likely to meet anything bigger than a frigate, but if you do you'll probably regret it.
An Indiaman is the biggest sort of ship you'll meet normally. These are built like two-decked fighting ships, but are less well armed with a smaller crew and with much less fighting spirit. An Indiaman is likely to be carrying valuable cargo, and lots of it. An Indiaman is a tough target, and if you attack one you could easily come off second best.
A Spanish Indiaman might turn out to be a treasure ship, carrying gold and silver plundered from the New World back to Spain.