Comment by anh_n

A server has more compute power but only needed if the problem to solve requires such power. In my last company I developed a visual search system (similar to Google Image Search) and for that use cases a powerful server is required. But for the problems this app try to solve like human detection or facial recognition, a mobile device is very capable of. In the last 2-3 years the new phones also has integrated AI chip, which make the task easier.