Crown molding has a beveled back used to project out from the top of the wall and meet the ceiling.
Casing molding is used around door ways and windows. Backband is used to beef up the casing.
Baseboard molding is used to hide the gap from your wall to your floor.
Panel molds are used to add profile to square edges or add to flat surfaces.
Chair rail molding is typically used as a wall divide to break up large wall space.
Cabinet corners have a beveled back used to be inserted into the corner of cabinets.