The big difference between the two boat storage methods comes down to the water. A dock is the area next to a pier or structure, where a slip is the water between piers.
So, what is a boat dock? A boat dock is an area of water between or next to a man-made structure that are involved in handling boats or ships. This area is open on three sides- a boat can easily move forward and backward. A dock is not necessarily a structure but a watery location. The word has been mostly used to describe the structures, such as piers, but it is the area beside them. The openness of a dock is the main feature that allows it to function in it’s specific way.
A boat slip, on the other hand, is a built structure. It is a portion of a pier or float where a boat is moored for setting sail or returning from a journey. A slip is not as open as a dock; it’s open on one end only. This can serve multiple vessels within one area whose sides are lined with piers. The main characteristic is the one open end as the sides break up swells that enter the marina. Having the piers alongside boats make it easier and more secure to board, especially when water conditions are less than ideal. A boat slip is a more preferred method to keeping your boat safe and allowing easy access to your vessel.