As you can see, there is one with a protruded head and the other one with a receiving cavity. What is the best and correct way to name them?
male / female connection part
mortise & tenon joints
I wouldn't call it a mortise and tenon joint, that is a woodworking term where one piece of wood is fitted into another. This looks like some kind of clip. Mortise and tenon joints don't clip together. If I needed to describe the connectors I would use "the male/female part" to describe it.
Apply a thin coat of glue to the male part of the clip...