Potato Flour vs. Regular Flour

Potato flour is made from potatoes and is gluten free.  It's often available in the kosher food section of your grocery, if you live in a larger urban area.

Regular flour is made of wheat - usually bleached and enriched.  You can get flours from any other grain as well - I use millet in recipes in the summertime because it's a "cooling" grain.  Most small grain flours are higher in gluten and can trigger allergies in sensitive dogs. 

So potato flour would be better to use then? Or anything that isn't from a grain?

It depends on your goals and dog's needs.  Probably the potato flour  is to make the recipe gluten free or allergy friendly.  If that is what you need, then yes, you'll want Potato or tapioca flour or rice flour if your dog tolerates that.  If that doesn't matter, then you can use wahtever you fancy and your dog likes or tolerates!  Most dogs do just fine with regular flour - it's what most dog biscuits are made of.  I think dogs find oat flour or cornmeal a little more tasty - if you've got a dog that will let you - go ahead and experiment to find what he or she likes best!