What I've found, and correct me if I'm wrong, but the UK reports convictions while in the US it's incidents. If you have a sources which have a neutral bias (AKA no agenda) which accurately compares death rates by the same standard I'd like to see it.
If anyone wants to compare US statistics without regards to the vast diversity of the US as a whole I suggest looking at VT where there are virtually no handgun restrictions and allow for statistical variation and I think we'd find that it sits well with fixed cultures in the EU.
Some areas of the US don't care about life and some do.
As per the UN the US has a homicide rate nearly four times that of the U.K.
http://www.businessinsider.com/oecd-homicide-rates-chart-2015-6