trash vs junk

trash and junk both are nouns.

Word	Noun	Adjective	Verb	Adverb
trash	Yes	No	Yes	No
junk	Yes	No	Yes	No

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

Other hyponyms of trash include scrap metal, debris, detritus, dust, rubble, litter.

As verbs, trash and junk are synonyms defined as:

Other synonyms of trash include scrap.

trash (noun)	junk (noun)
an amphetamine derivative (trade name Methedrine) used in the form of a crystalline hydrochloride; used as a stimulant to the nervous system and as an appetite suppressant	any of various Chinese boats with a high poop and lugsails
nonsensical talk or writing	the remains of something that has been destroyed or broken up
worthless people
worthless material that is to be disposed of

trash (verb)	junk (verb)
express a totally negative opinion of	dispose of (something useless or old)
dispose of (something useless or old)