reddish brown vs mahogany

reddish brown and mahogany both are nouns.

Word	Noun	Adjective	Verb	Adverb
reddish brown	Yes	No	No	No
mahogany	Yes	No	No	No

As nouns, reddish brown and mahogany are synonyms defined as:

Other synonyms of reddish brown include burnt sienna, sepia, Venetian red.

reddish brown (noun)	mahogany (noun)
a shade of brown with a tinge of red	a shade of brown with a tinge of red
	any of various tropical timber trees of the family Meliaceae especially the genus Swietinia valued for their hard yellowish- to reddish-brown wood that is readily worked and takes a high polish
	wood of any of various mahogany trees; much used for cabinetwork and furniture