err vs mistake

err is not a noun while mistake is a noun.

Word	Noun	Adjective	Verb	Adverb
err	No	No	Yes	No
mistake	Yes	No	Yes	No

As verbs, err and mistake are synonyms defined as:

Other synonyms of err include slip.

err (noun)	mistake (noun)
	a wrong action attributable to bad judgment or ignorance or inattention
	an understanding of something that is not correct
	part of a statement that is not correct

err (verb)	mistake (verb)
to make a mistake or be incorrect	to make a mistake or be incorrect
wander from a direct course or at random	identify incorrectly