snap ring vs fastener

snap ring and fastener both are nouns.

Word	Noun	Adjective	Verb	Adverb
snap ring	Yes	No	No	No
fastener	Yes	No	No	No

As nouns, fastener is a hypernym of snap ring; that is, fastener is a word with a broader meaning than snap ring:

snap ring: an oblong metal ring with a spring clip; used in mountaineering to attach a rope to a piton or to connect two ropes
fastener: restraint that attaches to something or holds something in place

Other hypernyms of snap ring include fastening, fixing, holdfast, hoop, ring, climbing equipment, rock-climbing equipment.

snap ring (noun)	fastener (noun)
an oblong metal ring with a spring clip; used in mountaineering to attach a rope to a piton or to connect two ropes	restraint that attaches to something or holds something in place
	a person who fastens or makes fast