A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying goods or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished from boats, based on size, shape, load capacity, and tradition.
A tugboat is a small sturdy and powerful vessel designed to push or tow other vessels and barges
You will see them in every sizable port; smart, businesslike small ships, low in the water and surging out to a large inbound ship. Tugs represent power for pushing and pulling, an engine with just enough hull for adequate buoyancy. Thick fenders for close-quarters work, pushing a big ship alongside the quay against the wind, hauling her off at the end of a towing wire.
Everyone knows what a submarine is - a ship that can go underwater. Hardly needs any explanation. Unless you're in the US Navy. By the Navy definition, only their modern, nuclear-powered boats ( all submarines are called "boats" ) are true submarines, designed to operate beneath the surface almost indefinitely. Anything else is merely a "submersible", tied to the surface by the need for fuel and air. Whatever.
A liner is a vessel designed primarily to carry passengers on a set schedule. There was a time when ocean liners were more than the mere pleasure cruisers of today. Before the advent of modern air travel, ships were the primary means of transport for those needing to cross the oceans. Untold numbers of immigrants came to this country in passenger liners, most in steerage class, a far cry from the modern floating pleasure palaces.
A packet ship of the early 1800s. Of note is the way the sails on the mainmast are set backward, against the sails on the fore- and mizzen- masts. Known as "backing", this was how a square-rigged ship "put on the brakes" to slow or stop without actually furling the sails.
Wind power has been used by mankind for millennia. Almost every human culture has constructed sailing vessels of some kind, from crude log or reed rafts to the highly developed wind-jammers of the early twentieth century. Many of these vessels were the most complex and technologically advanced machines of their time - equivalent to our jet airliners.
Steamer is an early term for any vessel power by a steam engine rather than sails.
Early steamers were propelled by large paddlewheels. "Side-wheelers", with the paddlewheels on each side, were more seaworthy, and therefore more common in ocean waters, while "stern-wheelers", with a single large paddlewheel at the back, were more common as riverboats. Later, these were replaced by more efficient screw (or propeller) vessels.