The difference between those are
1. You'll get the same package(code+documentation) for both of them
2. Both of the license is for single domain use
3. None of the license gives you the permission to resell the script.
4. With extended license you can modify the script and resell it. But this is also a bit complex. You can't just change some css , forms and resell it. Actually it's like "You can buy an extended license for a music and use it in your game. But you can't just change something and sell it as a music again" .