Foam Mattress is constructed out of foam. Usually supplied vacuum wrapped.
Open coil Mattress is a collection of steel springs tied together with links supported with a perimeter rod of either nylon or steel.
Pocket sprung mattress contains individual springs inserted into a material pocket.
Memory foam 'visco elastic' mattresses are constructed on either foam block, coil spring or pocket spring.
Latex mattresses are available as 100% latex or on coil or pocket springs.