writer vs scribbler

writer and scribbler both are nouns.

Word	Noun	Adjective	Verb	Adverb
writer	Yes	No	No	No
scribbler	Yes	No	No	No

As nouns, scribbler is a hyponym of writer; that is, scribbler is a word with a more specific, narrower meaning than writer:

writer (noun)	scribbler (noun)
writes (books or stories or articles or the like) professionally (for pay)	a writer whose handwriting is careless and hard to read
a person who is able to write and has written something	informal terms for journalists