Indian red vs reddish brown

Indian red and reddish brown both are nouns.

Word	Noun	Adjective	Verb	Adverb
Indian red	Yes	No	No	No
reddish brown	Yes	No	No	No

As nouns, reddish brown is a hypernym of Indian red; that is, reddish brown is a word with a broader meaning than Indian red:

Indian red: a reddish-brown color resembling the red soil used as body paint by American Indians
reddish brown: a shade of brown with a tinge of red

Other hypernyms of Indian red include burnt sienna, mahogany, sepia, Venetian red.

Indian red (noun)	reddish brown (noun)
a reddish-brown color resembling the red soil used as body paint by American Indians	a shade of brown with a tinge of red
a red soil containing ferric oxide; often used as a pigment
a red pigment composed in part from ferric oxide which is often used in paints and cosmetics