http://en.wikipedia.org/wiki/Dachau_concentration_camp
Treblinka, built to implement the "Final Solution," was a death camp. There was a railroad siding, facilities to undress the victims and process ( = steal) their belongs, gas chambers, and crematoria. The only barracks (besides those for the SS guards) were for the few Jews who were kept alive briefly to help run the place. The only "work" that was done there was related to killing people.
Dachau was a prison, albeit a very nasty, awful, evil prison. Treblinka was a factory for turning human beings into ashes.
Dachau was a concentration camp. Its principle reason for existing was to hold prisoners. Many died from overwork, guard brutality, and executions. But its principle function was not the direct murder of arriving inmates. That dubious distinction belonged to Treblinka, Chelmno, Belzec, Sobibor, and Birkenau [ and the sixth, whose name i can’t recall].