upkeep vs fixture

upkeep and fixture both are nouns.

Word	Noun	Adjective	Verb	Adverb
upkeep	Yes	No	No	No
fixture	Yes	No	No	No

As nouns, fixture is a hypernym of upkeep; that is, fixture is a word with a broader meaning than upkeep:

Other hypernyms of upkeep include fix, fixing, mend, mending, repair, reparation.

upkeep (noun)	fixture (noun)
activity involved in maintaining something in good working order	the act of putting something in working order again
the act of sustaining life by food or providing a means of subsistence	an object firmly fixed in place (especially in a household)
	the quality of being fixed in place as by some firm attachment
	a regular patron