It's more gun deaths in the US.

If you compare to Canada which, compared to all Western countries besides the US, has comparatively lax gun laws and high firearms ownership rates and a similar overall culture:

  * US sees 12.21 firearms deaths per capita per year to Canada's 1.94.
  * US sees 4.46 homicides via firearm per capita per year to Canada's 0.52.

(The UK stacks up at 0.20 and 0.02, so significantly lower still.)

This pattern holds over basically all numbers relating to rates of violence at every level of division.