bar vs rail

bar and rail both are nouns.

Word	Noun	Adjective	Verb	Adverb
bar	Yes	No	Yes	No
rail	Yes	No	Yes	No

As nouns, rail is a hyponym of bar; that is, rail is a word with a more specific, narrower meaning than bar:

bar: a rigid piece of metal or wood; usually used as a fastening or obstruction or weapon
rail: a horizontal bar (usually of wood or metal)

As nouns, rail is a hypernym of bar; that is, rail is a word with a broader meaning than bar:

bar: (law) a railing that encloses the part of the courtroom where the judges and lawyers sit and the case is tried
rail: a barrier consisting of a horizontal bar and supports

Other hypernyms of bar include railing.

bar (noun)	rail (noun)
the act of preventing	any of numerous widely distributed small wading birds of the family Rallidae having short wings and very long toes for running on soft mud
a rigid piece of metal or wood; usually used as a fastening or obstruction or weapon	a horizontal bar (usually of wood or metal)
an obstruction (usually metal) placed at the top of a goal	a bar or pair of parallel bars of rolled steel making the railway along which railroad cars or other vehicles can roll
a room or establishment where alcoholic drinks are served over a counter	a barrier consisting of a horizontal bar and supports
a counter where you can obtain food or drink	short for railway
a block of solid substance (such as soap or wax)
(law) a railing that encloses the part of the courtroom where the judges and lawyers sit and the case is tried
a heating element in an electric fire
a horizontal rod that serves as a support for gymnasts as they perform exercises
a narrow marking of a different color or texture from the background
musical notation for a repeating pattern of musical beats
the body of individuals qualified to practice law in a particular jurisdiction
a submerged (or partly submerged) ridge in a river or along a shore
(meteorology) a unit of pressure equal to a million dynes per square centimeter

bar (verb)	rail (verb)
prevent from entering; keep out	complain bitterly
render unsuitable for passage	spread negative information about
secure with, or as if with, bars	criticize severely
expel, as if by official decree	fish with a handline over the rails of a boat
	lay with rails
	travel by rail or train
	separate with a railing
	convey (goods etc.) by rails
	provide with rails
	enclose with rails