internment vs impounding

internment and impounding both are nouns.

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

As nouns, internment and impounding are synonyms defined as:

internment and impounding: placing private property in the custody of an officer of the law

Other synonyms of internment include impoundment, poundage.

internment (noun)	impounding (noun)
the act of confining someone in a prison (or as if in a prison)	placing private property in the custody of an officer of the law
placing private property in the custody of an officer of the law
confinement during wartime