atomic bomb vs atom bomb

atomic bomb and atom bomb both are nouns.

Word	Noun	Adjective	Verb	Adverb
atomic bomb	Yes	No	No	No
atom bomb	Yes	No	No	No

As nouns, atomic bomb and atom bomb are synonyms defined as:

atomic bomb and atom bomb: a nuclear weapon in which enormous energy is released by nuclear fission (splitting the nuclei of a heavy element like uranium 235 or plutonium 239)

Other synonyms of atomic bomb include A-bomb, fission bomb, plutonium bomb.

atomic bomb (noun)	atom bomb (noun)
a nuclear weapon in which enormous energy is released by nuclear fission (splitting the nuclei of a heavy element like uranium 235 or plutonium 239)	a nuclear weapon in which enormous energy is released by nuclear fission (splitting the nuclei of a heavy element like uranium 235 or plutonium 239)