HFC vs greenhouse gas

HFC and greenhouse gas both are nouns.

Word	Noun	Adjective	Verb	Adverb
HFC	Yes	No	No	No
greenhouse gas	Yes	No	No	No

As nouns, greenhouse gas is a hypernym of HFC; that is, greenhouse gas is a word with a broader meaning than HFC:

HFC: a fluorocarbon emitted as a by-product of industrial manufacturing
greenhouse gas: a gas that contributes to the greenhouse effect by absorbing infrared radiation

Other hypernyms of HFC include fluorocarbon, greenhouse emission.

HFC (noun)	greenhouse gas (noun)
a fluorocarbon emitted as a by-product of industrial manufacturing	a gas that contributes to the greenhouse effect by absorbing infrared radiation