atomic weapon vs H-bomb

atomic weapon and H-bomb both are nouns.

Word	Noun	Adjective	Verb	Adverb
atomic weapon	Yes	No	No	No
H-bomb	Yes	No	No	No

As nouns, H-bomb is a hyponym of atomic weapon; that is, H-bomb is a word with a more specific, narrower meaning than atomic weapon:

atomic weapon: a weapon of mass destruction whose explosive power derives from a nuclear reaction
H-bomb: a nuclear weapon that releases atomic energy by union of light (hydrogen) nuclei at high temperatures to form helium

atomic weapon (noun)	H-bomb (noun)
a weapon of mass destruction whose explosive power derives from a nuclear reaction	a nuclear weapon that releases atomic energy by union of light (hydrogen) nuclei at high temperatures to form helium