A point is a position in a buffer where editor commands take effect. The current point is generally between the character indicated by the cursor and the previous character (that is, it actually lies between two characters). Many types of commands (that is, moving, inserting, deleting) operate with respect to the current point, and indeed move that point.
The position of a point can be saved for later reference by setting a mark. Marks may either be set explicitly or as side effects of commands. More than one mark may be associated with a single buffer and saved in what is known as a mark ring. As for points, the positions of marks in a buffer are remembered even if that buffer is not currently being displayed.
A location is the position of the current point in a buffer at some time in the past. Locations are recorded automatically by commands that take you to a different buffer or where you might lose your place within the current buffer. They are designed to be a more comprehensive form of the mark ring but without the interaction with the selected region.
LispWorks Editor User Guide (Windows version) - 9 Dec 2014