spice up vs flavour

spice up is not a noun while flavour is a noun.

Word	Noun	Adjective	Verb	Adverb
spice up	No	No	Yes	No
flavour	Yes	No	Yes	No

As verbs, flavour is a hypernym of spice up; that is, flavour is a word with a broader meaning than spice up:

Other hypernyms of spice up include flavor, season.

spice up (noun)	flavour (noun)
	the taste experience when a savoury condiment is taken into the mouth
	(physics) the six kinds of quarks
	the general atmosphere of a place or situation and the effect that it has on people

spice up (verb)	flavour (verb)
make more interesting or flavorful	lend flavor to
add herbs or spices to