steam heating vs heating

steam heating and heating both are nouns.

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

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

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

Other hypernyms of steam heating include heat, heating plant, heating system.

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