There are multiple times in the film where Snoke takes a report directly from Hux, or gives Hux direct orders-- this implies that Snoke finds Hux to be useful. In that situation, Kylo Ren would probably not want to harm Hux, for fear of angering Snoke.
Another issue to consider is that, in the original trilogy, Vader had fallen almost fully to the dark side. Conversely, Kylo Ren hasn't fallen fully because he still "feels the pull to the light"; he has to actively will himself to remain in the dark.
The end result is that, when Vader is angry, he casually kills high-ranking members of the Imperial military. When Ren is angry, he smashes inanimate objects.