purple-red vs purplish-red

purple-red is not a noun while purplish-red is a noun.

Word	Noun	Adjective	Verb	Adverb
purple-red	No	Yes	No	No
purplish-red	Yes	Yes	No	No

As adjectives, purple-red and purplish-red are synonyms defined as:

purple-red (noun)	purplish-red (noun)
	a red with a tinge of purple

purple-red (adjective)	purplish-red (adjective)
of red tinged with purple	of red tinged with purple