scrap vs junk

scrap and junk both are nouns.

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

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

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

As verbs, scrap and junk are synonyms defined as:

Other synonyms of scrap include trash.

scrap (noun)	junk (noun)
the act of fighting; any contest or struggle	any of various Chinese boats with a high poop and lugsails
a small piece of something that is left over after the rest has been used	the remains of something that has been destroyed or broken up
a small fragment of something broken off from the whole
worthless material that is to be disposed of

scrap (verb)	junk (verb)
make into scrap or refuse	dispose of (something useless or old)
have a disagreement over something
dispose of (something useless or old)