gasmask vs respirator

gasmask and respirator both are nouns.

Word	Noun	Adjective	Verb	Adverb
gasmask	Yes	No	No	No
respirator	Yes	No	No	No

As nouns, gasmask and respirator are synonyms defined as:

gasmask and respirator: a protective mask with a filter; protects the face and lungs against poisonous gases

Other synonyms of gasmask include gas helmet.

gasmask (noun)	respirator (noun)
a protective mask with a filter; protects the face and lungs against poisonous gases	a breathing device for administering long-term artificial respiration
	a protective mask with a filter; protects the face and lungs against poisonous gases