What is difference between web server and proxy server?

What is the difference between a packet filter and a proxy?

Preface

So you think you know what a proxy is? Well if you are familiar with the old Web Proxy servers please forget everything you thought you knew about proxies. We are talking about something very different. The old proxy servers took web requests from clients and checked to see if it had that page already cached, and if not, it would then redirect the client request to the internet, if the request was allowed. A linear flowchart would look something like:

• Client request for KnowtheNetwork.com -> Proxy checks cache -> Not found, forward request
• Client request for google.com -> Proxy checks cache -> Cached page found, replies w/ cached page
• Client request for badwebsite.com -> Proxy checks cache -> Proxy denies the request based on policy

A modern day proxies are entirely different.