polyurethane foam vs PU

polyurethane foam and PU both are nouns.

Word	Noun	Adjective	Verb	Adverb
polyurethane foam	Yes	No	No	No
PU	Yes	No	No	No

As nouns, PU is a hypernym of polyurethane foam; that is, PU is a word with a broader meaning than polyurethane foam:

polyurethane foam: a foam made by adding water to polyurethane plastics
PU: any of various polymers containing the urethane radical; a wide variety of synthetic forms are made and used as adhesives or plastics or paints or rubber

Other hypernyms of polyurethane foam include polyurethan, polyurethane, PUR.

polyurethane foam (noun)	PU (noun)
a foam made by adding water to polyurethane plastics	any of various polymers containing the urethane radical; a wide variety of synthetic forms are made and used as adhesives or plastics or paints or rubber