Plimsoll mark vs Plimsoll line

Plimsoll mark and Plimsoll line both are nouns.

Word	Noun	Adjective	Verb	Adverb
Plimsoll mark	Yes	No	No	No
Plimsoll line	Yes	No	No	No

As nouns, Plimsoll mark and Plimsoll line are synonyms defined as:

Plimsoll mark and Plimsoll line: waterlines to show the level the water should reach when the ship is properly loaded

Other synonyms of Plimsoll mark include load line, Plimsoll.

Plimsoll mark (noun)	Plimsoll line (noun)
waterlines to show the level the water should reach when the ship is properly loaded	waterlines to show the level the water should reach when the ship is properly loaded