Hi Peter, and welcome to the club.
It is very difficult to determine differences between Jaguar specifications, as there are so many optional extras that can be specified by the first owner and factory fitted when being built.
My S Type SE is the top of the range, but having nothing to do I checked the price the optional extras cost and they came to £10,094.
A different engine will cost more, but the optional extras could make the cheaper [less expensive] model have a better spec.
But meanwhile, just enjoy your Jaguar.
Regards,
Peter