1. What is the difference (注意不是different,这里要用名词形式)/similarity AMONG these 3 pictures?
2. What is the difference/ similarity BETWEEN these 2 pictures?
3. What is the difference/ similarity AMONY Beijing, Shanghai and Guangzhou?
4. What is the difference/ similarity AMONY New York, Chicago, Washington and Los Angeles?
如果你想表达问有"哪些"不同点时就用:What are the differences/ similarities.