steam fitting vs upkeep

steam fitting and upkeep both are nouns.

Word	Noun	Adjective	Verb	Adverb
steam fitting	Yes	No	No	No
upkeep	Yes	No	No	No

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

steam fitting: care (installation and maintenance) of equipment for ventilating or heating or refrigerating
upkeep: activity involved in maintaining something in good working order

Other hypernyms of steam fitting include care, maintenance.

steam fitting (noun)	upkeep (noun)
care (installation and maintenance) of equipment for ventilating or heating or refrigerating	activity involved in maintaining something in good working order
	the act of sustaining life by food or providing a means of subsistence