I'm not an expert on the topic and don't really know the difference. But in the video they say it can finetune power delivery to individual parts of the SoC and reduce idle power.
About "fine tune" part, this does not relate to PMIC(or VRM) at all, more like CPU design: How many power domain does this CPU have ?
I assume Apple probably do that more than I know, it is just interesting that their vertical acquisition history feels the most boring and the most interesting.
At least looking from the outside, it feels like relatively small pieces develop into pretty big differentiators, like P.A. Semi, Intrinsity and Passif paving the way to their SoCs.