jack ladder vs Jacob's ladder

jack ladder and Jacob's ladder both are nouns.

Word	Noun	Adjective	Verb	Adverb
jack ladder	Yes	No	No	No
Jacob's ladder	Yes	No	No	No

As nouns, jack ladder and Jacob's ladder are synonyms defined as:

jack ladder and Jacob's ladder: (nautical) a hanging ladder of ropes or chains supporting wooden or metal rungs or steps

Other synonyms of jack ladder include pilot ladder.

jack ladder (noun)	Jacob's ladder (noun)
(nautical) a hanging ladder of ropes or chains supporting wooden or metal rungs or steps	(nautical) a hanging ladder of ropes or chains supporting wooden or metal rungs or steps
	pinnate-leaved European perennial having bright blue or white flowers