credit line vs by-line

credit line and by-line both are nouns.

Word	Noun	Adjective	Verb	Adverb
credit line	Yes	No	No	No
by-line	Yes	No	No	No

As nouns, credit line and by-line are synonyms defined as:

credit line and by-line: a line giving the name of the writer of a story or article

credit line (noun)	by-line (noun)
a line giving the name of the writer of a story or article	an auxiliary activity
the maximum credit that a customer is allowed	a line giving the name of the writer of a story or article