scarlet vs reddish

scarlet is a noun but reddish is not a noun.

Word	Noun	Adjective	Verb	Adverb
scarlet	Yes	Yes	No	No
reddish	No	Yes	No	No

As adjectives, scarlet and reddish are synonyms defined as:

scarlet and reddish: of a color at the end of the color spectrum (next to orange); resembling the color of blood or cherries or tomatoes or rubies

Other synonyms of scarlet include blood-red, carmine, cerise, cherry-red, cherry, crimson, red, ruby-red, ruby, ruddy.

scarlet (noun)	reddish (noun)
a variable color that is vivid red but sometimes with an orange tinge

scarlet (adjective)	reddish (adjective)
of a color at the end of the color spectrum (next to orange); resembling the color of blood or cherries or tomatoes or rubies	of a color at the end of the color spectrum (next to orange); resembling the color of blood or cherries or tomatoes or rubies