HFC vs greenhouse emission

HFC and greenhouse emission both are nouns.

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

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

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

Other hypernyms of HFC include fluorocarbon, greenhouse gas.

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