What is the difference between Proxy and firewall?

Firewall is component (Hardware or software) used to prevent unauthorized network access

Proxy have many types, the proxy server used to allow clints to make indirect connection to some network service.

The primary purpose of a firewall is to prevent unauthorized people from establishing a connection and gaining access to your network. In contrast, a proxy server’s main purpose is to act as a relay in order to facilitate the connection between two points.

Proxy server acts as a relay agent and forwards packets on behalf on certain user, whereas a firewall is primarily meant for packet filtering and access control implementation ...

The Firewall can act ( Configured ) as a proxy, but the proxy couldnt act ( be configured ) as a firewall

A proxy server and a firewall are both components of network security. They are similar in that they block or limit connections to and from your network, but they do this in different ways. Firewalls can block programs and ports that they try to gain unauthorized access to your computer. And proxy servers mainly hide your internal network from the internet. Proxy Server works as a firewall in the sense that it blocks your network from being exposed to the internet by redirecting web request when necessary.