Labour camps: concentration camps where interned inmates had to do hard physical labor under inhumane conditions and cruel treatment. Some of these camps were sub-camps of bigger camps, or "operational camps", established for a temporary need.

Transit and collection camps: camps where inmates were collected and routed to main camps, or temporarily held.

POW camps: concentration camps where prisoners of war were held after capture. These POW's endured torture and liquidation on a large scale.

Camps for rehabilitation and re-education of Poles: Camps where the intelligentsia of the ethnic Poles were held, and "re-educated" in light of German-Nazi values as slaves.

Hostage camps: camps where hostages were held and killed as reprisals.

Extermination Camps: These camps differed from the rest, since not all of them were also concentration camps. Although none of the categories is independent, and each camp could be classified as a mixture of several of the above, and all camps had some of the elements of an extermination camp, systematic extermination of new-arrivals occurred in very specific camps. Of these, four were extermination camps, where all new-arrivals were simply killed – the "Aktion Reinhard" camps (Treblinka, Sobibór, and Bełżec), together with Chelmo. Two others (Auschwitz and Majdanek) were combined concentration and extermination camps. Others were at times classified as "minor extermination camps."