Milky Way vs Milky Way Galaxy

Milky Way and Milky Way Galaxy both are nouns.

Word	Noun	Adjective	Verb	Adverb
Milky Way	Yes	No	No	No
Milky Way Galaxy	Yes	No	No	No

As nouns, Milky Way and Milky Way Galaxy are synonyms defined as:

Milky Way and Milky Way Galaxy: the galaxy containing the solar system; consists of millions of stars that can be seen as a diffuse band of light stretching across the night sky

Other synonyms of Milky Way include Milky Way System.

Milky Way (noun)	Milky Way Galaxy (noun)
the galaxy containing the solar system; consists of millions of stars that can be seen as a diffuse band of light stretching across the night sky	the galaxy containing the solar system; consists of millions of stars that can be seen as a diffuse band of light stretching across the night sky