The names of these plans will let you know how you are going to pay for it. Prepaid means that you are going to pay for what you are going to consume ahead of time, which means that you can limit your usage correctly. Postpaid implies that you are going to pay for what you have consumed up to a specific time.
Postpaid plans will allow you to have seemingly unlimited credits to text, call, and surf the web, but the price that you have to pay will differ depending on how much you use it. Take note that prepaid credits do not last forever too. Some will let you know just how long you can use the credits. If you do not consume the credits before the said date, then the credits will only be wasted.
A prepaid plan is a type of plan that comes with limited credits. For example, you will load 300 to your account, and this means that you can use up the 300, but the moment that you have finished it, you will not be able to connect online anymore or call and text other people that you want to contact.
When you have a postpaid plan, you can always be connected to people, but this does not mean that the things that you do are unlimited. The only difference is that you will never run out of load or internet connection. The problem with this is that it can be costly, especially if you tend to overuse your postpaid plan.