Afraid & Scared - means scared, concern, worried & feeling unsure

    I am afraid/scared of dogs.
    Why are you afraid/scared?
    My dogs are not afraid/scared of cats.
    Are you afraid/scared of the water?

Frightened - afraid or nervous

    That noise frightened me.
    We are to frightened to speak out.
    The donkey helped me when I was frighted.
    Don't frighten my donkey!!!!!

Tip:Frightened can be used as a verb or an adjective.
- See more at: http://english-the-easy-way.com/Confusing_English/Scared_Afraid_Frighten.html#sthash.gD2muqfj.dpuf