string line vs baulk-line

string line and baulk-line both are nouns.

Word	Noun	Adjective	Verb	Adverb
string line	Yes	No	No	No
baulk-line	Yes	No	No	No

As nouns, string line and baulk-line are synonyms defined as:

string line and baulk-line: line across a billiard table behind which the cue balls are placed at the start of a game

Other synonyms of string line include balkline.

string line (noun)	baulk-line (noun)
line across a billiard table behind which the cue balls are placed at the start of a game	line across a billiard table behind which the cue balls are placed at the start of a game