s 20 of OAPA 1861

S20 Inflicting GBH & S20 Wounding are two separate crimes; the mens rea for them both is the intention or recklessness to cause some harm, but they have two different actus reus'.

S20 GBH is serious or really serious harm (DPP v Smith) which can be physical or psychological and would include injuries such as broken bones, dislocated joints, injuries which result in a lengthy treatment, severe psychiatric injury which is more than fear or distress which requires specialist treatment etc etc etc

However, S20 Wounding is the breaking of both layers of skin, but internal bleeding doesn't constitute as being wounding (Eisenhower).

If the victim's skin doesn't break then the offence could be anything from battery to S18 GBH, which includes ABH. And so, if there is no wounding involved, depending on the severity of the injury, the defendant can be charged battery, ABH or GBH. For there to be a conviction of ABH, there must be an injury that is more than trivial that interferes with health and comfort and so a defendant could very well be charged with ABH, but it is all depending on the severity of the harm.

I hope that answers your question!!!