attachment vs fixation

attachment and fixation both are nouns.

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

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

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

attachment (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
the act of attaching or affixing something	the activity of fastening something firmly in position
faithful support for a cause or political party or religion	an unhealthy and compulsive preoccupation with something or someone
a supplementary part or accessory	an abnormal state in which development has stopped prematurely
a connection that fastens things together
a writ authorizing the seizure of property that may be needed for the payment of a judgment in a judicial proceeding
a feeling of affection for a person or an institution