Cable news people call them “prison camps” or “Trump prison camps,” but look in any dictionary: prisons are where people convicted of crimes are held. As Merriam-Webster notes, a prison is:
“[A]n institution for confinement of persons convicted of serious crimes.”
But what do you call a place where people who’ve committed no criminal offense (immigration violations are civil, not criminal, infractions)? The fine dictionary people at Merriam-Webster note the proper term is “concentration camp”:
“[A] place where large numbers of people (such as prisoners of war, political prisoners, refugees, or the members of an ethnic or religious minority) are detained or confined under armed guard.”
So these prisoners are not being held in a prison. English is silly sometimes.
They’re also imprisoned. Though to be fair, all languages are silly sometimes.
But a more accurate word to describe them might be captives, rather than prisoners. But both are correct