clutter up vs fill up

clutter up and fill up both are verbs.

Word	Noun	Adjective	Verb	Adverb
clutter up	No	No	Yes	No
fill up	No	No	Yes	No

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

Other hypernyms of clutter up include fill, make full.

clutter up (verb)	fill up (verb)
fill a space in a disorderly way	make full, also in a metaphorical sense
	become full
	eat until one is sated
	fill or stop up