Soviet Gulags were exceptionally harsh prisons. Survival was occasionally impossible but this was not by design - the state simply did not care if the inmates survived or not and wanted what they produced during the course of their sentence.

Official data is that of 18 million people sentenced to Gulags between 1930 and 1953, approximately 10% perished.

Gulag

Nazi camps came in two varieties. Ordinary concentration camps were all that Gulags were, no more and no less - an extension of the prison system for the undesirables. The Nazi definition of an undesirable was somewhat different from the Soviet definition and included homosexuals and some religious minorities (Jews, but also Jehovah witnesses and a few others). The idea was to extract some useful value from the inmates whilst they lived. Death rates were substantially higher than in Gulags, with up to 70% inmates dying while in captivity.

The other variety were extermination camps (Tötungszentren, killing centers), those dedicated to ending the human life as quickly as possible. There were only four dedicated killing centers: Chelmno, Belzec, Sobibor and Treblinka. The infamous Auschwitz-Birkenau was half and half, half work camp and half killing center.

To sum up, the Nazi concentration camps that weren’t killing centers might as well be Gulags in what they were and how they operated, though perhaps far more deadly (accuracy of data depending). Killing centers, well, nomen est omen.