coupler vs coupling

coupler and coupling both are nouns.

Word	Noun	Adjective	Verb	Adverb
coupler	Yes	No	No	No
coupling	Yes	No	No	No

As nouns, coupler and coupling are synonyms defined as:

coupler and coupling: a mechanical device that serves to connect the ends of adjacent objects

coupler (noun)	coupling (noun)
a mechanical device that serves to connect the ends of adjacent objects	the act of pairing a male and female for reproductive purposes
	a mechanical device that serves to connect the ends of adjacent objects
	a connection (like a clamp or vise) between two things so they move together