What's the difference

What's the difference? There are four pictures for each question , One of them different , come to find out it !

============ Game features ==============

1. Simple, fast-paced
2. The most appropriate to pass the time
3. Brainstorm, brain activation
4. Cute style , the public image
5. The young and old , healthy game
6. Category rich , ever-changing
7. The quiz is updated regularly