governor vs controller

governor and controller both are nouns.

Word	Noun	Adjective	Verb	Adverb
governor	Yes	No	No	No
controller	Yes	No	No	No

As nouns, controller is a hypernym of governor; that is, controller is a word with a broader meaning than governor:

governor: a control that maintains a steady speed in a machine (as by controlling the supply of fuel)
controller: a mechanism that controls the operation of a machine

Other hypernyms of governor include control.

governor (noun)	controller (noun)
a control that maintains a steady speed in a machine (as by controlling the supply of fuel)	a mechanism that controls the operation of a machine
the head of a state government	someone who maintains and audits business accounts
	a person who directs and restrains