fastening vs tying

fastening and tying both are nouns.

Word	Noun	Adjective	Verb	Adverb
fastening	Yes	No	No	No
tying	Yes	No	No	No

As nouns, tying is a hyponym of fastening; that is, tying is a word with a more specific, narrower meaning than fastening:

Other hyponyms of fastening include bonding, soldering, doweling, earthing, grounding, linkage, ligature, welding, fixation.

fastening (noun)	tying (noun)
the act of fastening things together	the act of tying or binding things together
restraint that attaches to something or holds something in place