fastening vs fixation

fastening and fixation both are nouns.

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

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

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

fastening (noun)	fixation (noun)
the act of fastening things together	(histology) the preservation and hardening of a tissue sample to retain as nearly as possible the same relations they had in the living body
restraint that attaches to something or holds something in place	the activity of fastening something firmly in position
	an unhealthy and compulsive preoccupation with something or someone
	an abnormal state in which development has stopped prematurely