You are technically correct about the origin of 'concentration camp'. But this point in relation to the Holocaust is so pedantic as to border on denial.

Most people who died in the Holocaust did not die in 'concentration camps'. About a quarter of them were killed in mass shootings and buried in mass graves. Another quarter were sent to something better described as 'extermination facilities'. There was no camp and no concentration - all victims were gassed to death on arrival. The most famous concentration camp - Auschwitz - also had a facility like this where around a million people died immediately on arrival. While Auschwitz did have the standard features of concentration camps - imprisonment, starvation, forced labor, and brutal punishment and torture, most people who died in Auschwitz never experienced any of this - they were simply executed on arrival.

So, while the 'concentration camps' were of course unimaginably terrible - and not to excuse other crimes against humanity such as the Boer camps, the gulags, etc - to compare other atrocities to the Nazi Holocaust simply because of the presence of concentration camps erases and minimizes the true extent of Nazi crimes against Jews and Roma.