Acer japonicum vs Japanese maple

Acer japonicum and Japanese maple both are nouns.

Word	Noun	Adjective	Verb	Adverb
Acer japonicum	Yes	No	No	No
Japanese maple	Yes	No	No	No

As nouns, Acer japonicum and Japanese maple are synonyms defined as:

Acer japonicum and Japanese maple: leaves deeply incised and bright red in autumn; Japan

Other synonyms of Acer japonicum include full moon maple.

Acer japonicum (noun)	Japanese maple (noun)
leaves deeply incised and bright red in autumn; Japan	leaves deeply incised and bright red in autumn; Japan
	ornamental shrub or small tree of Japan and Korea with deeply incised leaves; cultivated in many varieties