Bit random I know, but I have finally found out what they mean.
Bio or Biological washing powder has enzymes (these are naturally occurring compounds) which help breakdown the fats which stick to clothes.
Non Bio does not have these but has other cleaning agents.
Transparently the UK is unique in selling both types, everywhere else they only sell bio washing powder as its more effective.
But Bio washing powder only works at low temperatures, the heat breaks the enzymes down, so the washing power is less effective, so its better for the environment, as well as saving you money. We design our baby bibs and baby accessories to be able to wash at low temperatures for this reason.