Walking distance accuracy in Health app

Today my beloved and I walked together the same distance with our iPhones in our pockets. I am 5” tall; he is 6”. We walked side by side at the exact same pace. At the end of our walk, his health app clocked him in at 3.7 miles. Mine calculated my distance as 2.1 miles. We’re both running iOS 17.2.1 with our apps up to date. We left the house right after we awoke so no extra distance there. On the map app, the distance one way is 1.1 mile. Factor in the walk to the car and a detour on the path, let’s say 1.5 miles one way. What would cause such a discrepancy? Why would my distance be .5 miles under and his .5 over?