There is no difference at all. Apple has the same kind of ‘monopoly‘ in AppStore that Tesco in their stores. You enter Tesco, you will find cheaper Tesco branded product directly competiting with other producers on the shelves . Tesco is both the owner of the shopping platform and the maker of the competiting product. Every smartphone maker has its own AppStore: Google Play, Samsung Store, Sony, Huawei, Amazon etc. IOS has 27% market share, the rest of the mobile market belongs to Android makers.