burnt umber vs deep brown

burnt umber and deep brown both are nouns.

Word	Noun	Adjective	Verb	Adverb
burnt umber	Yes	No	No	No
deep brown	Yes	No	No	No

As nouns, burnt umber and deep brown are synonyms defined as:

Other synonyms of burnt umber include chocolate, coffee, umber.

burnt umber (noun)	deep brown (noun)
a medium brown to dark-brown color	a medium brown to dark-brown color
dark brown pigment obtained by heating umber