scratch line vs starting line

scratch line and starting line both are nouns.

Word	Noun	Adjective	Verb	Adverb
scratch line	Yes	No	No	No
starting line	Yes	No	No	No

As nouns, scratch line and starting line are synonyms defined as:

scratch line and starting line: a line indicating the location of the start of a race or a game

Other synonyms of scratch line include scratch, start.

scratch line (noun)	starting line (noun)
a line indicating the location of the start of a race or a game	a line indicating the location of the start of a race or a game