The difference between a large prison compound and a concentration camp is not necessarily in the architecture, although concentration camps tended to be much larger and extended than average prisons.
The primary difference is whether the people inside have or have not been found guilty of crimes with an imprisonment sentence under the law in a fair trial under in full adherence to all human rights under international law.
If they have, it’s a prison. If they have not, it’s a concentration camp.
The difference is also whether you ever leave or not. Call it “quarantine camp” as much as you like but in the absence of a deadly pandemic (Covid mortality is comparable to flu mortality), and in the absence of a person being proven to be contagious from a considerably deadly disease, it’s a transition step towards concentration camps. You may be still be able to leave a “quarantine camp”, but for how long?
The next difference is the use of the forced labour of the inmates for the benefit of the government or associated corporations & physical detriment of the people within. Both prisons & concentration camps use the labour of the people within, but in concentration camps the labour is forced under the punishment of torture or death.