To track your steps, your sports app and our United Heroes app use the same pedometer (or "accelerometer"): the one on your phone. This one simply records the movements of your device. Then, our two services interpret this raw information using different methods to count your steps. We don't have details on how they work, but this explains these differences in the number of steps displayed.
The solution could be to enable the authorization to access your Position for our application from the Settings application of your phone on Applications and notifications > United H. > Authorizations? If the problem persists do not hesitate to contact us.