Dock (boat dock, wet dock, pier, harbor, dock slip) - A place where a boat is parked on water.
The main difference between a dock and a boat slip is that a dock is open to the water on three sides, while a boat slip is only open on one. Docks are usually more affordable to rent space at or built at a waterfront house, while boat slips are more expensive and take up more space.
Boat slips often have an F or U configuration to create a three-sided port with a single entry point. This design allows a boat to “slip” into this parking spot with ease, which is why these structures are called slips in the first place.
Berth: (verb) To bring a ship to a berth. (noun) The wharf space at which a ship docks. A wharf may have two or three berths, depending on the length of incoming ships.
A boat dock is the actual structure of wood or metal where you're parking the boat and putting boat dock accessories. Mooring at a boat dock means securing it parallel to the dock and leaving three sides open to the water.