The difference is described by the so called crop factor. The coolpix has a much smaller sensor compared to the EOS, thus it will photograph only a smaller section at the same lens focal length. In this case the sensor is so much smaller that it actually looks like it has a focal length longer than the longer actual focal length of the EOS. You basically have to apply a sensors size in the form of the crop factor to the focal length of the lens (and consequently also to the aperture) in order to arrive at the actual, effective focal length.