Is cap different from hat ?

Hats: use for a specific purpose, a declaration of modality, fines or religious affiliation, issue of a general declaration for a personal military exercise. The hat may denote ranges within such law enforcement positions. 

Caps: Can be used to block sunlight on the face.

Difference between cap and hat:

A cap and a hat are historical helmets that have been worn for many years for different purposes. However, An embargo that applies from the ground up and a Way-Interchangeable for watercolors that has no idea of differences. 

Although the appearance is almost similar, there are key differences between these headcovers as the article reveals.