"Concentration camp" has been used to describe Nazi death camps for a long time, and has come to be more-or-less synonymous. None of the Japanese camps systematically killed people, as far as I know. Manzanar was an atrocity, but it was not in the same league as Dachau. To call them both by same name is misleading.

That said, 'internment camp' sounds far too weak. From what I've read, every piece of property they couldn't carry was taken, and they were rounded up and forced to live in horse-stalls for the duration of the war. Every single family, as far as I know, had to not only suffer the indignity of being held without cause, but then had to rebuild from zero after the war. I can't think of a better term, but it needs one.