Those Japanese-American detainees had legal residential status when they were illegally rounded up without due process.

The detainees in the current border camps have no such status. Some of them are eventually admitted as refugees but there is no obligation to allow any of them to simply enter the country.

Presumably they would be permitted to leave the camps if they decided to go to a different country. If not, then the camps are in fact concentration camps. If so, then the comparison is hysterical political outrage that spits in the face of actual political detention.