Map Pedometer

I started using Map Pedometer about a year ago and I have mapped out a half-dozen routes in my neighbourhood. By the end of November I was walking a little faster than 10 minutes per kilometre. Or put another way, 6 km per hour according to the distances provided by Map Pedometer. I think that was fast enough for an old guy like me. Then I had an injury and took a break. In February this year, after my doctor gave me the OK, I started walking on a treadmill in my home. After a couple days, when I felt confident, just for fun, I set the treadmill to 6 km per hour and it was scary. I never walked that quickly outdoors.

So today I walked outdoors on a route that Map Pedometer says is 2.01 km. I did it in 19:44 which is a tiny bit faster than 6 km per hour. Then, I measured the belt on the treadmill and counted out 100 times around. The math shows that everything on the tradmill seems accurate.

I'm confused. Are the distances on the Map Pedometer that far out?

I think they are taken from google maps, which should be accurate, How many kilometers did the treadmill show? Running on a treadmill feels different from running normally.