blush vs redden

blush is a noun but redden is not a noun.

Word	Noun	Adjective	Verb	Adverb
blush	Yes	No	Yes	No
redden	No	No	Yes	No

As verbs, blush and redden are synonyms defined as:

Other synonyms of blush include crimson, flush.

As verbs, redden is a hypernym of blush; that is, redden is a word with a broader meaning than blush:

blush (noun)	redden (noun)
sudden reddening of the face (as from embarrassment or guilt or shame or modesty)
makeup consisting of a pink or red powder applied to the cheeks
a rosy color (especially in the cheeks) taken as a sign of good health

blush (verb)	redden (verb)
turn red, as if in embarrassment or shame	turn red, as if in embarrassment or shame
become rosy or reddish	turn red or redder
	make red