nerve gas vs G agent

nerve gas and G agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
nerve gas	Yes	No	No	No
G agent	Yes	No	No	No

As nouns, G agent is a hyponym of nerve gas; that is, G agent is a word with a more specific, narrower meaning than nerve gas:

nerve gas: a toxic gas that is inhaled or absorbed through the skin and has harmful effects on the nervous and respiratory system
G agent: a non-persistent nerve agent discovered and synthesized during or prior to World War II by Dr. Gerhard Schrader.

Other hyponyms of nerve gas include VX gas, organophosphate nerve agent, G-series agent, G-series nerve agent.

nerve gas (noun)	G agent (noun)
a toxic gas that is inhaled or absorbed through the skin and has harmful effects on the nervous and respiratory system	a non-persistent nerve agent discovered and synthesized during or prior to World War II by Dr. Gerhard Schrader.