What are the advantages of the topping quota? And what's the difference with data quota?

If you buy a topping quota, you can get more quota, access the applications you need at a cheaper price of course. You don't have to worry about running out of quota to use the application you like.

Well, the difference is, the data quota is the main quota for internet access which can be accessed by all applications, anytime, anywhere. Meanwhile, the topping quota is a special quota for accessing certain applications. For example the Instagram topping quota, now that's just for accessing Instagram.