You said eating an apple while driving is illegal and then said smoking had been added to the same list. None of these activities are illegal – however, if they cause you to fail to drive without due care and attention, you can be prosecuted. There is an important semantic difference because the present law could be applied equally to vaping – the only difference is that at present vaping is not noted in the CPS guidance, but that has no force in law.
EDIT: it is also worth noting that the CPS guidance only talks about lighting a cigarette.