Sounds like and is are two different things.

a person who has written a particular text.

"the writer of the letter"

a person who writes books, stories, or articles as a job or regular occupation.

"the distinguished travel writer Freya Stark"

Similar:

author

wordsmith

man/woman of letters

penman

creative writer

scribbler

scribe

pen-pusher

hack

potboiler

a person who writes in a specified way.

"Dickens was a prolific writer"