junction vs joining

junction and joining both are nouns.

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

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

junction: an act of joining or adjoining things
joining: the act of bringing two things into contact (especially for communication)

Other hypernyms of junction include connection, connexion.

junction (noun)	joining (noun)
an act of joining or adjoining things	the act of bringing two things into contact (especially for communication)
the place where two or more things come together
something that joins or connects
the shape or manner in which things come together and a connection is made
the state of being joined together