What is the difference between at&t go phone plan and t-mobile prepaid?

[Nilly]

I've had the T-Mobile (NYSE: DT) prepaid plan but then I wanted a better phone so I got an AT&T go phone because I heard that you could use a sim card from a T-Mobile phone on an AT&T phone. But since it didn't work I decided to just stick with my AT&T phone.

[Medina Begovic]

When you buy a phone outright that means that it is a prepaid phone which needs prepaid credit. Prepaid credit means literally what it says: you pay for the amount of calls you are going to make BEFORE you actually make them. Whereas, a plan means that you probably have unlimited use and in the end however many calls you make that's how much you have to pay the company. Prepaid is good because you know your limit, however, once it runs out and you need a phone call ASAP you won't be able to make one unless you top up. Plans are good because phone calls are always at your disposal, however, you may get carried away and spend more than anticipated.