Fully synthetic depends on definition, in the UK a HC (hydro cracked base oil) can be called fully synthetic. In Germany it needs to be at least 80% synthetically created oil. Difference between mineral base oil, hydro crack and fully synthetic has to do with which molecule chains make up the oil.
Mineral oil is a mix of whatever happens to come out of fractioned distillation, hydro cracked you treat the mineral stuff to break up very long chains, so molecules that make up the oil are more similar but it's still a mix... synthetic base oils are dismantled on molecular level and reassembled, i.e. giving the most uniform base oil with the desired hydrocarbon chain length. The more you treat the base oil the more expensive it gets....
Most oils sold as fully synthetic in the UK are only HC, some do have varying lots of synthetic oil in them.
In a PD diesel you need an oil with EP (extreme pressure) additives due to the way the injection system works (all driven by cams). Which only 505.01 and 507.00 has. You will find a lot of oils that sound similar to the ones with said specs because they use the same or similar base oil but have varying additive packages (which most oil companies buy in ready formulated from specialist companies, e.g. Infineum).
Just as a bit of boring bed time reading if you can't fall asleep.
