Would this be abh or gbh?

It's been a few years since I studied law at college but my understanding of ABH and GBH was that GBH was any physical attack which left a mark or a bruise and ABH was any attack wich broke the skin or flesh. So my answer to your scenario would be, A would be guilty of ault causing GBH if B was not bleeding. A would be guilty of ault causing ABH if B WAS bleeding, however if B died from his injuries it would become Involuntary Manslaughter if A did not intend to kill B, or Murder if he did.