producer gas vs air gas

producer gas and air gas both are nouns.

Word	Noun	Adjective	Verb	Adverb
producer gas	Yes	No	No	No
air gas	Yes	No	No	No

As nouns, producer gas and air gas are synonyms defined as:

producer gas and air gas: a gas made of carbon monoxide and hydrogen and nitrogen; made by passing air over hot coke

producer gas (noun)	air gas (noun)
a gas made of carbon monoxide and hydrogen and nitrogen; made by passing air over hot coke	a gas made of carbon monoxide and hydrogen and nitrogen; made by passing air over hot coke