isotope vs deuterium

isotope and deuterium both are nouns.

Word	Noun	Adjective	Verb	Adverb
isotope	Yes	No	No	No
deuterium	Yes	No	No	No

As nouns, deuterium is a hyponym of isotope; that is, deuterium is a word with a more specific, narrower meaning than isotope:

isotope: one of two or more atoms with the same atomic number but with different numbers of neutrons
deuterium: an isotope of hydrogen which has one neutron (as opposed to zero neutrons in hydrogen)

Other hyponyms of isotope include radioisotope, heavy hydrogen.

isotope (noun)	deuterium (noun)
one of two or more atoms with the same atomic number but with different numbers of neutrons	an isotope of hydrogen which has one neutron (as opposed to zero neutrons in hydrogen)