What is the difference between formal and informal socialization? which is more instrumental in forming ones political beliefs?

Formal socialization is the organized learning of skills, norms and information  such as in a school environment.

Informal socialization is the learning without formal structure, outside of an institution, such as with friends.

I would say that usually the informal socializing is more instrumental in forming political beliefs, but exceptions are also possible. 

Where is the map? explain the choices?