the question does probably sound stupid but.... better to ask than stay in a kind of fog concerning that point.
I now have some brushes ans stamps I've bought in DD store. In my files I have the.png and the.abr.
Most often I use the .abr.
But I'm wondering what is the difference between using a abr and using a png (do not forget I'm a real beginner and that I cannot spent as much tme as I would like on scrap and that is for both traditional and digital).