put behind bars vs jug

put behind bars is not a noun while jug is a noun.

Word	Noun	Adjective	Verb	Adverb
put behind bars	No	No	Yes	No
jug	Yes	No	Yes	No

As verbs, put behind bars and jug are synonyms defined as:

Other synonyms of put behind bars include gaol, immure, imprison, incarcerate, jail, lag, put away, remand.

put behind bars (noun)	jug (noun)
	a large bottle with a narrow mouth
	the quantity contained in a jug

put behind bars (verb)	jug (verb)
lock up or confine, in or as in a jail	stew in an earthenware jug
	lock up or confine, in or as in a jail