Google Maps is available in China per their documentation:
The Google Maps APIs are served within China from the domain maps.google.cn. This domain does not support https. When making requests to the Google Maps APIs from China, please replace https://maps.googleapis.com with http://maps.google.cn.
I have tested this outside China without any issues, however I can't find any documentation that prohibit developers from using http://maps.google.cn outside of china. Does anyone knows about any restrictions?
The answer is already stated in that description. The "https://maps.googleapis.com" or simply "https" is not supported in the China. That is why you need to use "http" and not "https". There is no problem with that outside of China because we can still access that http://maps.google.cn. The only issue is http is not a secured and the data is not encrypted, and it can be intercepted by third parties to gather data being passed between the two systems.
So if you are not in China, it is better to use the https://maps.googleapis.com. The http://maps.google.cn is only for the people who wants to use Google Map that is live in China.
Hope this information helps you.
