Memory doesn't help things go faster, unless you run out :) And if you run out, things then go very much slower.
There may be other differences between those two machines (BIOS, motherboard, timings, various performance overrides and tweaks) that are the cause of the difference. You will find plenty of results on the benchmark where the CPU and memory are the same, but the time to complete the benchmark is different, sometimes by quite a lot, and this is due to those other aspects of the hardware set up.