Strutted headboards have two reinforced struts (headboard legs) that attach the headboard securely to a divan base. This attachment is invisible when the bed is pushed against the wall.
A floorstanding headboard (aka a full height headboard) is a separate headboard unit that stands directly on the floor behind the bed frame. They can be attached to the divan base like strutted headboards, or placed behind the bed when it is pushed against the wall.