heavy hydrogen vs deuterium

heavy hydrogen and deuterium both are nouns.

Word	Noun	Adjective	Verb	Adverb
heavy hydrogen	Yes	No	No	No
deuterium	Yes	No	No	No

As nouns, heavy hydrogen and deuterium are synonyms defined as:

heavy hydrogen and deuterium: an isotope of hydrogen which has one neutron (as opposed to zero neutrons in hydrogen)

heavy hydrogen (noun)	deuterium (noun)
an isotope of hydrogen which has one neutron (as opposed to zero neutrons in hydrogen)	an isotope of hydrogen which has one neutron (as opposed to zero neutrons in hydrogen)