foam vs shaving foam

foam and shaving foam both are nouns.

Word	Noun	Adjective	Verb	Adverb
foam	Yes	No	Yes	No
shaving foam	Yes	No	No	No

As nouns, shaving foam is a hyponym of foam; that is, shaving foam is a word with a more specific, narrower meaning than foam:

foam: a mass of small bubbles formed in or on a liquid
shaving foam: toiletry consisting of a liquid preparation containing many small bubbles that soften the beard before shaving

Other hyponyms of foam include head, lather, lather, soapsuds, suds, spume, white water, whitewater.

foam (noun)	shaving foam (noun)
a mass of small bubbles formed in or on a liquid	toiletry consisting of a liquid preparation containing many small bubbles that soften the beard before shaving
a lightweight material in cellular form; made by introducing gas bubbles during manufacture

foam (verb)	shaving foam (verb)
become bubbly or frothy or foaming