Oh goodie - an oil thread....
LL01 is not spec'ed for engines with DPFs so the LL04 spec. was developed for later DPF-equiped engines and their more complex emission requirements. However, the LL04 spec. is somewhat backwards compatible with LL01 so can be used in your engine (but not gasoline engines in the USA/Oz etc.)
BMW-Oil-Specs-and-Recs.pdf
Having said that, I stick with an LL01 rated oil (on my Euro 3 M57TÜ) - Castrol Edge 5w/40 - as I don't want to pay for features in an oil that aren't required by my engine.
Different oils/brands may be tested against one spec but not others, so you can see a varied mix of specs on similar oils.
And BMW or Porsche don't rate oils - they release a spec. (requirements to be met) and oil manufactors test against these standards. Or not. An oil that meets Porsche A40 may well also pass LL01 but may not have actually been tested against that spec.