The difference will only be in any cleaning additives and similar added extras as all petrol and diesel has to meet a minimum quality standard.
The V-Power and similar 'more power' fuels I'm not sure how they add the extra octane/cetane - if it's just an additive to the standard stuff mixed in or actually made like that at the refinery.
The V-Power and similar 'more power' fuels I'm not sure how they add the extra octane/cetane - if it's just an additive to the standard stuff mixed in or actually made like that at the refinery.