Quizilla isn't as easy to write as Mibba. The format on Mibba just makes everything easier, and you can use BBCode on Mibba. (I don't know if you can use it on Quizilla or not, but it's much easier on Mibba, because they have tutorials and introductions.) The journals are posted on one section, and the story and poem making process is amazingly better. You can write articles and reviews and news on Mibba, you can chat on Mibba, you can use the forums on Mibba, and you can look at the new users page. There are so many differences. I used to be a Quizilla native and it really sucks a**.
Quizilla was sh*t the moment it was sold. I left that cess pool a few weeks ago after the site, once again, decided to screw with everyone's publishings.