Are tom's hardware charts actually true. I was comparing a sempron to a core 2 duo and difference wasn't much?

seriously i went on www.tomshardware.com and then i went on charts then processors and i went on 2008 processor comparision and there was the core 2 duo e7200 and another sempron 3100+ and they were encoding a 700 mb mpv into a 700 mb mp4 and the core 2 duo took 1 hour and a half and the sempron took only 2 hours and 15 minutes. Is that all the difference is between a core 2 duo and a sempron i thought the difference was mive and it showed that both the system's had the same vid card same amount of ram and the same os.