No Steve, they are not
Originally Posted by Steve Smith
Domestic/Car Diesel Pump nozzles are slightly larger than the Petrol versions.
This has been done to help prevent the unbelievably frequent case where inattentive people try and fill their Petrol car with Diesel (clogs the injectors and gives the catalyst a hard time) or putting Petrol in their Diesel car (washes the lubricating film off the cylinder bores and will quickly result in a seized engine)
Commercial Diesel Pump Nozzles are much bigger than those used for cars to help deliver a sensible flow rate when you need several hundred litres of fuel and don't want it to take all day - although the Lorry Diesel Pumps are usually round the back of the Petrol Station - away from the Canopy height restrictions and have less tight turns to get those very long vehicles on and off the forecourt.