Honestly, there isn't a difference program functionality wise (the program remains consistent throughout except for the UI skins which with higher plans Unity lets you customize the color and look / splash screens). The biggest difference between each from what I understand (and I am right here learning with ya!) is that you gain analytics, cloud storage, and a couple other features that are not crucial to the actual development of the game itself. Again, these tools are more so external from the unity game engine itself and can be implemented upon the launch of your game.

If you are just getting started, I really don't think you will want to deep dive into analytics until your game really gains traffic. So just stick to the personal until you make the next 'Angry Birds' :)