linkage vs fastening

linkage and fastening both are nouns.

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

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

Other hypernyms of linkage include attachment.

linkage (noun)	fastening (noun)
the act of linking things together	the act of fastening things together
a mechanical system of rods or springs or pivots that transmits power or motion	restraint that attaches to something or holds something in place
(genetics) traits that tend to be inherited together as a consequence of an association between their genes; all of the genes of a given chromosome are linked (where one goes they all go)
an associative relation