The differences between a yacht and a boat lie in the length, purpose and expense of the vessels, and these distinctions sometimes overlap.
A boat is a watercraft that is used for pleasure, commercial or residential purposes, whereas a yacht is used exclusively for pleasure and carries the connotation of luxury.
A boat is a watercraft that is less than 197 feet long from the tip of the bow to the end of the stern. A yacht is usually larger than 30 feet, but if it is luxurious enough, even a small boat can be referred to as a yacht.
A ship is a watercraft over 197 feet long that can also be used for pleasure, commercial or residential purposes; therefore, a yacht can be either a boat or a ship, depending on its length. A yacht over 100 feet is referred to as a megayacht; one over 150 feet is called a superyacht. There are yachts as long as 400 feet!