The bonus at first purchase between site and in-game top-up has huge difference

Look at the bonus differences of site and in-game top-up, the in-game top up offers more bonus unlike in site, it doubled the amount of genesis crystal while site offers 10-40% bonus only. The amount and price of genesis crystal are same, the only differences are bonus. But why is it like that? Also I'm looking for BP in the site top-up but it doesn't have, I wish Mihoyo will add BP there too. I want to buy BP there.