nexus vs linkage

nexus and linkage both are nouns.

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

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

nexus (noun)	linkage (noun)
a connected series or group	the act of linking things together
the means of connection between things linked in series	a mechanical system of rods or springs or pivots that transmits power or motion
	(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