First of all, I don't use any Nike products and can therefore not verify my answer myself.
All information is taken from the Nike+ Support page, though, so I'm pretty confident it's correct.
The most likely reason for your differing nikefuel gains is the device type. If you are using the SportsBand and your friend is using the RunningApp, your nikefuel is most likely calculated differently, as each device is optimized to track a certain type of activity.
As per the specific support page:
If you use multiple Nike+ devices, you may receive a different
NikeFuel amounts on each device for the same workout. That's because
each Nike+ device uses different technologies and are optimized for
For example, the SportWatch GPS is optimized for pace and distance and
is the best device for measuring those metrics if you are a runner or
walker, while the Nike+ FuelBand or FuelBand SE is optimized to
capture your everyday activity as NikeFuel and is the best option for
measuring your overall athletic life.
Feel free to wear both devices at once if you're interested in both
your sport-specific workout data and your overall activity data. Some
variation between the two is to be expected and shouldn't be cause for
(If my citation is violating any kind of copyright please edit it and/or let me know.)