imperial elephant vs imperial mammoth

imperial elephant and imperial mammoth both are nouns.

Word	Noun	Adjective	Verb	Adverb
imperial elephant	Yes	No	No	No
imperial mammoth	Yes	No	No	No

As nouns, imperial elephant and imperial mammoth are synonyms defined as:

imperial elephant and imperial mammoth: largest known mammoth; of America

Other synonyms of imperial elephant include Archidiskidon imperator.

imperial elephant (noun)	imperial mammoth (noun)
largest known mammoth; of America	largest known mammoth; of America