interconnection vs joining

interconnection and joining both are nouns.

Word	Noun	Adjective	Verb	Adverb
interconnection	Yes	No	No	No
joining	Yes	No	No	No

As nouns, joining is a hypernym of interconnection; that is, joining is a word with a broader meaning than interconnection:

interconnection: (computer science) the act of interconnecting (wires or computers or theories etc.)
joining: the act of bringing two things into contact (especially for communication)

Other hypernyms of interconnection include connection, connexion.

interconnection (noun)	joining (noun)
(computer science) the act of interconnecting (wires or computers or theories etc.)	the act of bringing two things into contact (especially for communication)
a state of being connected reciprocally