tune up vs tweak

tune up is not a noun while tweak is a noun.

Word	Noun	Adjective	Verb	Adverb
tune up	No	No	Yes	No
tweak	Yes	No	Yes	No

As verbs, tweak is a hyponym of tune up; that is, tweak is a word with a more specific, narrower meaning than tune up:

Other hyponyms of tune up include fine-tune, service, tune in.

tune up (noun)	tweak (noun)
	a squeeze with the fingers

tune up (verb)	tweak (verb)
adjust the pitches of (musical instruments)	adjust finely
adjust for (better) functioning	to be under the influence of methamphetamine
	pull or pull out sharply
	pinch or squeeze sharply