tear up vs shred

tear up is not a noun while shred is a noun.

Word	Noun	Adjective	Verb	Adverb
tear up	No	No	Yes	No
shred	Yes	No	Yes	No

As verbs, tear up and shred are synonyms defined as:

Other synonyms of tear up include rip up.

tear up (noun)	shred (noun)
	a small piece of cloth
	a tiny or scarcely detectable amount

tear up (verb)	shred (verb)
tear into shreds	tear into shreds