A motorboat generally speaking is a vessel other than a sailboat or personal watercraft, propelled by an internal combustion engine driving a jet or a propeller. A speedboat is a small motorboat designed to move quickly, used in races, for pulling water skiers, as patrol boats, and as fast-moving armed attack vessels by the military.
There are three popular variations of powerplants, inboard, inboard/outboard, and outboard.
If the engine is installed within the boat, it's called a powerplant; if it's a removable module attached to the boat, it's commonly known as an outboard motor.
An outboard motor is installed on the rear of a boat and contains the internal combustion engine, the gear reduction, and the propeller.
An inboard/outboard contains a hybrid of a powerplant and an outboard, where the internal combustion engine is contained inboard and the gear reduction and propeller are outside.
A purely inboard boat contains everything except a shaft and a propeller inside the vessel. There are two configurations of an inboard, v-drive and direct drive. A direct drive has the powerplant mounted near the middle of the boat with the propeller shaft straight out the back, where a v-drive has the powerplant mounted in the back of the boat facing backwards having the shaft go towards the front of the boat than making a 'V' towards the rear.
Motorboats vary greatly in size and configuration, from the 4-meter, open Boston Whaler type to the so-called "Bond villain" luxury mega-yachts capable of crossing an ocean.
