foam vs lather

foam and lather both are nouns.

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

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

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

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

Other hyponyms of foam include seethe.

foam (noun)	lather (noun)
a mass of small bubbles formed in or on a liquid	the froth produced by soaps or detergents
a lightweight material in cellular form; made by introducing gas bubbles during manufacture	the foam resulting from excessive sweating (as on a horse)
	a workman who puts up laths
	agitation resulting from active worry

foam (verb)	lather (verb)
become bubbly or frothy or foaming	rub soap all over, usually with the purpose of cleaning
	exude sweat or lather
	form a lather
	beat severely with a whip or rod