Japanese maple vs Acer japonicum

Japanese maple and Acer japonicum both are nouns.

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

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

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

Other synonyms of Japanese maple include full moon maple.

Japanese maple (noun)	Acer japonicum (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