Yes, there is definitely a difference between single-action baking powder and double-acting baking powder. single-acting baking powder reacts immediately when mixed with liquid ingredients. Double-acting baking powder, on the other hand, reacts in two stages: first when mixed with liquid and then when exposed to heat during baking.
Most commercial baking powders are double-acting, which provides more leeway in the baking process. Homemade baking powder substitutes tend to act like single-acting baking powder, so it's important to bake your goods immediately after mixing the ingredients.