Actual bodily harm would be something like a bruise, greivous would be a broken bone or stabbing or the like. Sentencing largely depends on which way the wind is blowing and whether the judge's wife is talking to him at that time.

Grievous bodily harm means 'really serious bodily injury' and in the UK 'g.b.h.' means an offence under section 18 of the Offences Against the Person Act 1861 of causing grievous bodily harm with intent, the maximum penalty for which is life imprisonment. Actual bodily harm (a.b.h.)is any lesser injury, although, technically,causing a split to the skin sufficient to cause bleeding is simply wounding,and may be so charged (though both fall within section 20 of the Act and are of much less gravity)