Box spring and Futon

Box spring noun - A coiled bedspring in a frame that is covered with cloth.

Futon and box spring are semantically related. in bedding topic. In some cases you can use "Futon" instead a noun phrase "Box spring".

Futon noun - Mattress consisting of a pad of cotton batting that is used for sleeping on the floor or on a raised frame.

Box spring and futon are semantically related. You can use "Box spring" instead a noun "Futon".