signal tower vs signal box

signal tower and signal box both are nouns.

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

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

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

signal tower (noun)	signal box (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