Crux vs Southern Cross

Crux and Southern Cross both are nouns.

Word	Noun	Adjective	Verb	Adverb
Crux	Yes	No	No	No
Southern Cross	Yes	No	No	No

As nouns, Crux and Southern Cross are synonyms defined as:

Crux and Southern Cross: a small conspicuous constellation in the Southern Hemisphere in the Milky Way near Centaurus

Other synonyms of Crux include Crux Australis.

Crux (noun)	Southern Cross (noun)
a small conspicuous constellation in the Southern Hemisphere in the Milky Way near Centaurus	a small conspicuous constellation in the Southern Hemisphere in the Milky Way near Centaurus