We have national crime recording standards. So assaults etc. are all recorded for the stats. Crimes with no victim, or where the victim is the Crown, generally aren't recorded (speeding etc.)
That's the theory. In practice recording varies. The Met, for example, won't record some offences by telephone whereas others do, so that keeps their stats low. In other areas crimes which could be either recordable or are non-recordable (discharging a firearm could be an offence against the Crown or against the person being shot) are recorded according to how the Chief Constable wants to massage the figures. It's supposed to be the most serious recorded, but it's up to the crime recorder how they interpret the alleged facts.