carouse vs wassail

carouse and wassail both are nouns.

Word	Noun	Adjective	Verb	Adverb
carouse	Yes	No	Yes	No
wassail	Yes	No	Yes	No

As verbs, wassail is a hypernym of carouse; that is, wassail is a word with a broader meaning than carouse:

carouse: engage in boisterous, drunken merrymaking
wassail: celebrate noisily, often indulging in drinking; engage in uproarious festivities

Other hypernyms of carouse include jollify, make happy, make merry, make whoopee, racket, revel, whoop it up.

carouse (noun)	wassail (noun)
revelry in drinking; a merry drinking party	a punch made of sweetened ale or wine heated with spices and roasted apples; especially at Christmas

carouse (verb)	wassail (verb)
engage in boisterous, drunken merrymaking	propose a toast to
	celebrate noisily, often indulging in drinking; engage in uproarious festivities