slop jar vs pail

slop jar and pail both are nouns.

Word	Noun	Adjective	Verb	Adverb
slop jar	Yes	No	No	No
pail	Yes	No	No	No

As nouns, pail is a hypernym of slop jar; that is, pail is a word with a broader meaning than slop jar:

slop jar: a large pail used to receive waste water from a washbasin or chamber pot
pail: a roughly cylindrical vessel that is open at the top

Other hypernyms of slop jar include bucket.

slop jar (noun)	pail (noun)
a large pail used to receive waste water from a washbasin or chamber pot	a roughly cylindrical vessel that is open at the top
	the quantity contained in a pail