Sender: 

The person who send a message to  someone. The sender is the originator of the message. 

Example: The person who write a letter to her friend .The person is the sender.

Receiver:

Receiver one who intercepts and decodes a message. The receiver is the destination of the message.

Example:

Telephone receivers which transform electrical impulses into audio signals, and radio or television receivers, which accept electromagnetic waves and convert them into sound or television pictures.