ORC most likely would credit a bit more as routing would include sector SEA-DFW, which is around 1600 miles more. SEA-LHR direct and DFW-LHR are more or less same mileage. Also booking class for AA First might add to the credited amount, as F would give 300%. BA J and AA A both being 250% do not make any difference.

I donīt know if BA credits ORC to other FFPs, in your case to AY. AY only credits you what AY gets from BA.