Pithecanthropus erectus vs genus Pithecanthropus

Pithecanthropus erectus and genus Pithecanthropus both are nouns.

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

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

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

Other synonyms of Pithecanthropus erectus include Pithecanthropus.

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