PFC vs greenhouse gas

PFC and greenhouse gas both are nouns.

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

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

PFC: a powerful greenhouse gas emitted during the production of aluminum
greenhouse gas: a gas that contributes to the greenhouse effect by absorbing infrared radiation

Other hypernyms of PFC include fluorocarbon, greenhouse emission.

PFC (noun)	greenhouse gas (noun)
a powerful greenhouse gas emitted during the production of aluminum	a gas that contributes to the greenhouse effect by absorbing infrared radiation