Sleeper sofa and Sofa bed

Sofa bed and sleeper sofa are semantically related in pull-out sofa topic. In some cases you can use "Sofa bed" instead a noun phrase "Sleeper sofa".

Sofa bed noun - A sofa that can be converted into a bed.

Sleeper sofa and sofa bed are semantically related in couch that becomes bed topic. You can use "Sleeper sofa" instead a noun phrase "Sofa bed".