If CECOT isn’t a concentration camp, then what is it?

So if no prisoner is ever released from CECOT once detained, which is essentially a life sentence, how is this not a concentration camp?

People go there to die. Whether they die at the hands of the prison guards, from the poor conditions of the prison (starvation , dehydration, etc), or they live a long life and die naturally, people go in there and they don’t come out. These people go to this prison and they die.

If this is not a concentration camp, then what is it? I don’t know of any other prison that does not allow its prisoners to leave , or even have the rights to an appellate process. Even in the US , prisoners on death row can still access their lawyers, and they have the opportunity to appeal their case.

So if a very specific prison will not let the prisoners the opportunity to leave , and if they are kept in a facility currently over max capacity , sleeping on metal bunks with no blankets or pillows and with lights on 24/7, hardly given the opportunity to shower or use the restroom, god knows what other horrifying conditions, and they live like that until they die…. how is this not a concentration camp? Can anyone explain that?