fixation vs fastening

fixation and fastening both are nouns.

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

As nouns, fastening is a hypernym of fixation; that is, fastening is a word with a broader meaning than fixation:

Other hypernyms of fixation include attachment.

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