What is the difference between a proxy server and a reverse proxy server?

A simple definition would be:

• Forward Proxy: Acting on behalf of a requestor (or service consumer)
• Reverse Proxy: Acting on behalf of service/content producer.

Example:

Setting up a proxy in your browser so that Netflix doesn’t know what country you’re in is a forward proxy; an upstream service that directs an incoming request (perhaps you want to send one request to two servers) is a reverse proxy.