In Oz we get full synthetic Castrol Edge 5W30 A3/B4 which is ACEA A3/B4, API SL/CF, BMW Longlife-01, MB-Approval 229.3/ 229.5, VW 502 00/ 505 00.
We also get full synthetic Castrol Magnatec Stop-Start 5W30 which is ACEA A3/B4 and API SN.
Both are full synthetics (Group III) but the Edge has elevated ZDDP (about 1000 ppm Phos I hear) while the Magnatec has norm ILSAC levels of ZDDP (probably about 800 ppm Phos). It's all in the Phos levels which are restricted for ILSAC-RC viscosity grades (e.g. 0W20, 5W30, etc) in API SN, but not for thicker oils (e.g. 0W40, 5W40, 20W50, etc), and not for API SL.
Hence M1 or Edge 0W40 can have 1000ppm Phos and 1100 ppm Zinc and be A3/B4 and API SN, while the same quality oil with the same ZDDP levels in Edge 5W30 must be A3/B4 and API SL.
Castrol says about their Edge 5W30 A3/B4 "Passes all engine test performance requirements of API SN and SM but exceeds Phosphorus limits of those classifications." Unfortunately this wording has been removed from their most recent PDS, but I saved a copy of the old PDS, and that is a direct cut & paste quote from Castrol.