Pithecanthropus vs Pithecanthropus erectus

Pithecanthropus and Pithecanthropus erectus both are nouns.

Word	Noun	Adjective	Verb	Adverb
Pithecanthropus	Yes	No	No	No
Pithecanthropus erectus	Yes	No	No	No

As nouns, Pithecanthropus and Pithecanthropus erectus are synonyms defined as:

Pithecanthropus and Pithecanthropus erectus: former genus of primitive apelike men now Homo erectus

Other synonyms of Pithecanthropus include genus Pithecanthropus.

Pithecanthropus (noun)	Pithecanthropus erectus (noun)
former genus of primitive apelike men now Homo erectus	former genus of primitive apelike men now Homo erectus