snarl up vs snarl

snarl up is not a noun while snarl is a noun.

Word	Noun	Adjective	Verb	Adverb
snarl up	No	No	Yes	No
snarl	Yes	No	Yes	No

As verbs, snarl up and snarl are synonyms defined as:

snarl up and snarl: make more complicated or confused through entanglements

Other synonyms of snarl up include embrangle.

snarl up (noun)	snarl (noun)
	something jumbled or confused
	a vicious angry growl
	an angry vicious expression

snarl up (verb)	snarl (verb)
make more complicated or confused through entanglements	make more complicated or confused through entanglements
	utter in an angry, sharp, or abrupt tone
	make a snarling noise or move with a snarling noise
	twist together or entwine into a confusing mass