Devices calculate your stride length based on your height and sometimes even your pace. Each device calculates the stride length slightly differently.
So, how does this affect your challenge?
Well, depends on the challenge. Most challenges are counted in steps, so the stride length isn't really a factor.
However, Journey challenges are tracked by distance in miles. In a Journey you may see some players in the lead with a small amount of steps because they have a longer stride. You can check out our Steps to Distance calculator to estimate how many steps you get per mile based off of your height and pace.