atomic power vs nuclear energy

atomic power and nuclear energy both are nouns.

Word	Noun	Adjective	Verb	Adverb
atomic power	Yes	No	No	No
nuclear energy	Yes	No	No	No

As nouns, nuclear energy is a hypernym of atomic power; that is, nuclear energy is a word with a broader meaning than atomic power:

atomic power: nuclear energy regarded as a source of electricity for the power grid (for civilian use)
nuclear energy: the energy released by a nuclear reaction

Other hypernyms of atomic power include atomic energy.

atomic power (noun)	nuclear energy (noun)
nuclear energy regarded as a source of electricity for the power grid (for civilian use)	the energy released by a nuclear reaction