lion monkey vs lion marmoset

lion monkey and lion marmoset both are nouns.

Word	Noun	Adjective	Verb	Adverb
lion monkey	Yes	No	No	No
lion marmoset	Yes	No	No	No

As nouns, lion monkey and lion marmoset are synonyms defined as:

lion monkey and lion marmoset: small South American marmoset with silky fur and long nonprehensile tail

Other synonyms of lion monkey include leoncita, tamarin.

lion monkey (noun)	lion marmoset (noun)
small South American marmoset with silky fur and long nonprehensile tail	small South American marmoset with silky fur and long nonprehensile tail