signal box vs signal tower

signal box and signal tower both are nouns.

Word	Noun	Adjective	Verb	Adverb
signal box	Yes	No	No	No
signal tower	Yes	No	No	No

As nouns, signal box and signal tower are synonyms defined as:

signal box and signal tower: a building from which signals are sent to control the movements of railway trains

signal box (noun)	signal tower (noun)
a building from which signals are sent to control the movements of railway trains	a building from which signals are sent to control the movements of railway trains