Aircraft can generally be divided in aeronautical vehicles and thrust vehicles. Thrust vehicles keep themselves aloft by the thrust of their engines, while aeronautical vehicles use aeronautic lift to keep aloft.
Aeronautical vehicles can be divided into lighter-than-air aerostats that derive their lift from buoyancy and heavier-than-air vehicles that use aerodynamic lift, generated by pushing a wing through the air to generate lift.
Heavier than air vehicles using aerodynamic lift can be divided into airplanes that push their lifting surfaces forward in the direction of motion to generate lift, kites and gliders that instead have their lifting surfaces forward pulled through the air to generate lift, and rotorcraft that rotate their lifting surfaces round and round to generate lift.
Rotorcraft can be divided into units which rotate the aerodynamic lift surface about a verical axis, and those that revolve around a horizontal axis.
Of those rotorcraft that use a vertical axis, they can be divided into: helicopters that derive lift by swinging a lifting surface around in a circle, like arms on a clock, with a connection point driven motion; rotordynes which like helicopters, rotate the lifting surface through a circle, but use tip mounted thrust units instead of a connection point powered unit; autogiros that let forward motion push the lifting surface around the central attachment point, by pushing the vehicle forward; rotor kites that are like autogiros, but which are pulled forward instead;
Of these, several aircraft are hybrids of these categories, and some deviate from the standard in some way, such as aerostats that are heavier-than-air, and use aerodynamic lift to overcome the lack of buoyancy.
Not all aeronautical vehicles are aircraft. Hovercraft, are not aircraft, though they depend on aerodynamic forces to lift the vehicle into the air. Hovercraft are extremely restricted in flight height, needing to be virtually in contact with the ground.