How accurate is a Pedometer compared  to a GPS

For measuring distance  over flat ground I think a pedometer can be just as good.

Take my walk yesterday as an example,

my pedometer said 19.4 miles walked over 5 hours 22 min’s

Geoff’s GPS said 19.1 miles in 5 hours 10 min’s.

Whether it would be so accurate over the hills I don’t know.

It has also been discussed here  with some interesting opinions.