heating vs steam heat

heating and steam heat both are nouns.

Word	Noun	Adjective	Verb	Adverb
heating	Yes	No	No	No
steam heat	Yes	No	No	No

As nouns, steam heat is a hyponym of heating; that is, steam heat is a word with a more specific, narrower meaning than heating:

heating: utility to warm a building
steam heat: a heating system in which steam is generated in boilers and piped to radiators

Other hyponyms of heating include central heating, gas heat, panel heating, steam heating.

heating (noun)	steam heat (noun)
utility to warm a building	a heating system in which steam is generated in boilers and piped to radiators
the process of becoming warmer; a rising temperature