There is a little bit of a difference between pancakes & hotcakes. Pancakes are very simple. Traditional US pancakes are made with flour, eggs, milk, & baking powder. On the other hand, hotcakes are made with flour, eggs, milk, baking powder, & either cornmeal, whole wheat flour, or oatmeal. Cornmeal, whole wheat flour, and oatmeal are added to hotcakes for more texture. You can make modifications to suit dietary restrictions.
Hotcakes were fed to the lumberjacks because they added oatmeal to them to set them up to work longer before lunch was required. I believe that hotcakes were cooked a little bit thicker as well. Where pancakes are more of a US thing, I’ve read that hotcakes are more of a UK thing.
I’m not sure that anybody eats hotcakes anymore & pancakes don’t seem to be as popular as they once were, so the phrase selling like hotcakes probably is a thing of the past.