When we talk about glasses we had seen different varieties of glasses. Smart glass and photochromic glass are exactly two types of glasses which are distinguished according to the material we use. Smart glass works based on the electrical requirements while photochromic glass works based on solar energy. As the name says photochromic glass converts to black when exposed to sunlight while smart glass purely works based on the switches and electrical connections.
Smart glass works based on the electrical power supply providing and the commands given to the glasses. The smart glass can be in any color. It may be milky, black or in any other shades. The glass color automatically changes to any color from transparent to opaque in a click. It can be used for office, house partitions etc. The partitions can be easily converted to a commonplace or a conference hall in a click. The best results are enjoyed in a mouse click by managing in mobile for both transparency and opacity.
Photochromic glass converts the color from transparent to opaque with the intensity of sun rays falling in the glass. The plain glass gets darker as the intensity of light falls on it. The glass can give you the opportunity to enjoy both clear glasses in the least sunlight while protection from UV rays in the daytime. The glasses can be used for pergolas, window pales, and in all the areas which require shade in the daytime while you want to enjoy a clear sky in the night.
Altogether we cannot assume better is either smart glass nor photochromic one, while both are different in their characteristics and functioning.