nuclear fusion vs nuclear fusion reaction

nuclear fusion and nuclear fusion reaction both are nouns.

Word	Noun	Adjective	Verb	Adverb
nuclear fusion	Yes	No	No	No
nuclear fusion reaction	Yes	No	No	No

As nouns, nuclear fusion and nuclear fusion reaction are synonyms defined as:

nuclear fusion and nuclear fusion reaction: a nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy

Other synonyms of nuclear fusion include fusion.

nuclear fusion (noun)	nuclear fusion reaction (noun)
a nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy	a nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy