The ER's have an extra fuel tank holding approx 10,000kgs. this tank is at the rear of the forward hold ie just in front of the Centre Wing Tank and the potable water tanks that are in this position in the standard B744 have been moved to the rear of the aircraft. The new BRW is approx 18 tonnes heavier than the earlier aircraft and to support this the wing off the B744F has been fitted with stronger landing gear, brakes, tyres etc.
Minor changes on the flight deck with B777 style LCD's replacing the previous CRT's. Information is displayed in basically the same way with minor enhancements (eg colour changes to the yaw indicator (a rectangle at the base of the sky pointer) when an engine is shutdown). The fuel system controls on the overhead panel and the synoptic display have also been changed to provide for the new fuel tank. The main flight deck windows will be thicker to reduce the flight deck noise levels.
The cabin interiors have been updated with B777 style overhead bins etc.