Japanese deer vs Cervus sika

Japanese deer and Cervus sika both are nouns.

Word	Noun	Adjective	Verb	Adverb
Japanese deer	Yes	No	No	No
Cervus sika	Yes	No	No	No

As nouns, Japanese deer and Cervus sika are synonyms defined as:

Japanese deer and Cervus sika: small deer of Japan with slightly forked antlers

Other synonyms of Japanese deer include Cervus nippon, sika.

Japanese deer (noun)	Cervus sika (noun)
small deer of Japan with slightly forked antlers	small deer of Japan with slightly forked antlers