Thank you ucbalumnus, that was enlightening.
So German-Americans and Italian-Americans were detained on an individual basis based on lack of citizenship status/perceived national security risk.
Japanese-Americans were forced to relocate/detained in camps wholesale, because of their ethnicity. I am sure it was unconstitutional at the time.
It’s easier if you can tell a person is “other” just by looking at them, right? Try doing that with persons of German ancestry in the US.