Crime data along with other law enforcement data is generally collected and reported the same way in both the us and uk as they both use internationally accepted ways of data collection advocated by the united nations, ngos, and research institutions
here's an interesting article that goes into detail about some of the fuckery with regards to crime statistic reporting in the UK.
http://www.theendrun.com/larry-pratt-british-gun-crime-stats-a-sham