A recipient is generally a person who gets something.
A receiver can be the same, but it also means an electronic device that receives signals.
Receiver has some more meanings such as ;
-In American football it is the player who is good at being in the right place to catch the ball that is thrown.
-A person who receives stolen goods
-The person whom the court appoints to manage the financial affairs of someone who is bankrupt.
Not a teacher.