The difference between a 'forward' and 'reverse' proxy is determined by where the proxy is running. For example, your ISP probably uses a web cache to reduce its bandwidth costs. In this case, the proxy is sitting between your computer and the whole Internet. This is a 'forward proxy'. The proxy has a limited set of users (the ISP's customers), and can forward requests on to any machine on the Internet (i.e. the web sites that the customers are browsing).
Alternatively, a company can put a web cache in the same data center as their web servers, and use it to reduce the load on their systems. This is a 'reverse proxy'. The proxy has an unlimited set of users (anyone who wants to view the web site), but proxies requests on to a specific set of machines (the web servers running the company's web site). This is a typical role for Traffic Managers - they are traditionally used as a reverse proxy.