sunbather vs bum

sunbather and bum both are nouns.

Word	Noun	Adjective	Verb	Adverb
sunbather	Yes	No	No	No
bum	Yes	Yes	Yes	No

As nouns, bum is a hypernym of sunbather; that is, bum is a word with a broader meaning than sunbather:

Other hypernyms of sunbather include do-nothing, idler, layabout, loafer.

sunbather (noun)	bum (noun)
someone who basks in the sunshine in order to get a suntan	the fleshy part of the human body that you sit on
	a vagrant
	a person who is deemed to be despicable or contemptible
	person who does no work

sunbather (adjective)	bum (adjective)
	of very poor quality; flimsy

sunbather (verb)	bum (verb)
	ask for and get free; be a parasite
	be lazy or idle