registration vs ingress

registration and ingress both are nouns.

Word	Noun	Adjective	Verb	Adverb
registration	Yes	No	No	No
ingress	Yes	No	No	No

As nouns, ingress is a hypernym of registration; that is, ingress is a word with a broader meaning than registration:

Other hypernyms of registration include entering, entrance, entry, incoming.

registration (noun)	ingress (noun)
the act of enrolling	the act of entering
the act of adjusting something to match a standard	(astronomy) the disappearance of a celestial body prior to an eclipse
(music) the sound property resulting from a combination of organ stops used to perform a particular piece of music; the technique of selecting and adjusting organ stops
a document certifying an act of registering
the body of people (such as students) who register or enroll at the same time