red mulberry vs mulberry tree

red mulberry and mulberry tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
red mulberry	Yes	No	No	No
mulberry tree	Yes	No	No	No

As nouns, mulberry tree is a hypernym of red mulberry; that is, mulberry tree is a word with a broader meaning than red mulberry:

red mulberry: North American mulberry having dark purple edible fruit
mulberry tree: any of several trees of the genus Morus having edible fruit that resembles the blackberry

Other hypernyms of red mulberry include mulberry.

red mulberry (noun)	mulberry tree (noun)
North American mulberry having dark purple edible fruit	any of several trees of the genus Morus having edible fruit that resembles the blackberry