Dry erase markers are used to mark the surface of a dry erase board with a message or drawing. Dry erase markers, also know as whiteboard markers are specially designed to use erasable ink. The non toxic erasable markers can be used by children and easily erased when done. Make sure you keep the cap on though because the ingredient that makes them erasable can also evaporate.
Wet erase markers require the use of a liquid or solvent to wipe of the semi-permanent ink. You can use them on a range of non-pourus surface including whiteboards, mirrors or even windows. A damp cloth is usually enough to get recently applied wet erase marker ink off of your surface but there are specially formulated cleaners available if you would rather use them to clean of wet erase markers.