I'm no oil expert, but I read that on a Ford forum. For what is worth, Mobil 1 advanced Synthetic also meets both 925A and 945A:
Protection for the maximum interval between recommended oil changes.
Helps to reduce fuel consumption.
Meets the requirements of Chrysler HEMI engines with MDS (Multi Displacement Systems).
Produced using a patented blend of high performance synthetic base oils, fortified with a precisely balanced system of constituents.
Specially designed to help provide unequalled levels of performance, cleansing power and engine protection, meeting the performance standard requirements ILSAC GF-4.
Meets or exceeds: API SN, SN RESOURCE CONSERVING, SM, SM Energy Conserving, SL, SJ; ILSAC GF-4, GF-5; ACEA A1/B1; Ford WSS-M2C925-A, FORD WSS-M2C945-A, WSS-M2C930-A; Chrysler MS-6395.
Recommended by ExxonMobil for applications that require: API CF; ILSAC GF-4, GF-3; GM 6049M.
So the only difference is probably the UV dye they put in the Castrol to help them void your warranty if you go with another oil manufacturer?