bomb shelter vs air-raid shelter

bomb shelter and air-raid shelter both are nouns.

Word	Noun	Adjective	Verb	Adverb
bomb shelter	Yes	No	No	No
air-raid shelter	Yes	No	No	No

As nouns, bomb shelter and air-raid shelter are synonyms defined as:

bomb shelter and air-raid shelter: a chamber (often underground) reinforced against bombing and provided with food and living facilities; used during air raids

Other synonyms of bomb shelter include bombproof.

bomb shelter (noun)	air-raid shelter (noun)
a chamber (often underground) reinforced against bombing and provided with food and living facilities; used during air raids	a chamber (often underground) reinforced against bombing and provided with food and living facilities; used during air raids