brick red vs reddish brown

brick red and reddish brown both are nouns.

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

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

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

brick red (noun)	reddish brown (noun)
a bright reddish-brown color	a shade of brown with a tinge of red