Apple had those clauses (I believe they are referred to as ‘Most Favored Nation’ clauses) but I believe removed them after the US E-Book settlement. They stil

Apple had those clauses (I believe they are referred to as ‘Most Favored Nation’ clauses) but I believe removed them after the US E-Book settlement. They still may be attached to marketing and partnership opportunities I believe, though - you might not be featured in the store if you charge iOS users more than android or web users, just like they will probably not advertise a new movie or album if Amazon is allowed to sell it for a lower price.