cumulonimbus vs cumulonimbus cloud

cumulonimbus and cumulonimbus cloud both are nouns.

Word	Noun	Adjective	Verb	Adverb
cumulonimbus	Yes	No	No	No
cumulonimbus cloud	Yes	No	No	No

As nouns, cumulonimbus and cumulonimbus cloud are synonyms defined as:

cumulonimbus and cumulonimbus cloud: a dark cloud of great vertical extent charged with electricity; associated with thunderstorms

Other synonyms of cumulonimbus include thundercloud.

cumulonimbus (noun)	cumulonimbus cloud (noun)
a dark cloud of great vertical extent charged with electricity; associated with thunderstorms	a dark cloud of great vertical extent charged with electricity; associated with thunderstorms