night letter vs wire

night letter and wire both are nouns.

Word	Noun	Adjective	Verb	Adverb
night letter	Yes	No	No	No
wire	Yes	No	Yes	No

As nouns, wire is a hypernym of night letter; that is, wire is a word with a broader meaning than night letter:

Other hypernyms of night letter include telegram.

night letter (noun)	wire (noun)
a cheaper form of telegram sent for delivery the next day	ligament made of metal and used to fasten things or make cages or fences etc
	a metal conductor that carries electricity over a distance
	a message transmitted by telegraph
	the finishing line on a racetrack

night letter (verb)	wire (verb)
	equip for use with electricity
	send cables, wires, or telegrams
	fasten with wire
	string on a wire
	provide with electrical circuits