tying vs ligation

tying and ligation both are nouns.

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

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

tying: the act of tying or binding things together
ligation: (surgery) tying a duct or blood vessel with a ligature (as to prevent bleeding during surgery)

tying (noun)	ligation (noun)
the act of tying or binding things together	(surgery) tying a duct or blood vessel with a ligature (as to prevent bleeding during surgery)