custody vs internment

custody and internment both are nouns.

Word	Noun	Adjective	Verb	Adverb
custody	Yes	No	No	No
internment	Yes	No	No	No

As nouns, internment is a hypernym of custody; that is, internment is a word with a broader meaning than custody:

Other hypernyms of custody include imprisonment.

custody (noun)	internment (noun)
holding by the police	the act of confining someone in a prison (or as if in a prison)
(with `in') guardianship over; in divorce cases it is the right to house and care for and discipline a child	placing private property in the custody of an officer of the law
a state of being confined (usually for a short time)	confinement during wartime