The actual fuel capacity of the -300 is much greater than the -200 (137,500kg vs 94,300kg),
In my company, we only have 200's, 94,300Kg refers to only 3 A Market of none ER 777's. All of the others, both GE and RR can carry 137,500Kg of fuel. But, the RR aircraft are rated for 297t, the GE either 267t or 275t depending on config. That said, typically the RR aircraft have the potential to carry more fuel for a given pax load.
At 297t out of SIN bound for LHR in the winter with Prestwick as a div due fog inthe south of the UK, the fuel load was around 113t....from AUH to MCT same aircraft it was as little as 11t.
Back on the thread a bit I always though the second two digit's on the Trents referred to the power rating, ie we have 895's....95K of thrust.