Sprint cancels reload means you can interrupt your reload if you suddenly need to move fast.
Reload while sprinting means while you are running you can reload 
By default you are unable to reload and sprint at the same time. If you have Sprint cancels reloading turned on then you are UNABLE to sprint until you finish the reloading.
I haven’t even tested them both at the same time, but I believe that the hard setting of Sprint Cancels reload would negate the reload while sprinting and you would need to start reloading again after you start moving. Can anybody test this or does anybody already know the answer?
Generally speaking it is always a good idea to have sprint cancels reload enabled IMHO, as not all mercs get access to that augment.