bum vs grub

bum and grub both are nouns.

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

As verbs, bum and grub are synonyms defined as:

Other synonyms of bum include cadge, mooch, sponge.

bum (noun)	grub (noun)
the fleshy part of the human body that you sit on	a soft thick wormlike larva of certain beetles and other insects
a vagrant	informal terms for a meal
a person who is deemed to be despicable or contemptible
person who does no work

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

bum (verb)	grub (verb)
ask for and get free; be a parasite	search about busily
be lazy or idle	ask for and get free; be a parasite