Difference Between Network Address Translation And Port Address Translation

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BASIS OF COMPARISON   NAT PAT
Description NAT translates the private local IP to the global public IP address. PAT translates the private IP addresses of an internal network to the public IP address with the help of port numbers.
Relationship NAT has a one-to-one or many-to-one relationship. PAT has a many-to-one relationship.
Types There are two types of NAT: Static NAT and  Dynamic NAT There are two types of PAT: static and overloaded PAT.
IPv4 NAT along with the IPv4 addressing scheme preserves IPv4 addresses and extends their lifespan. PAT uses the IPv4 address along with the port number.
Relations NAT is the superset of PAT. PAT is a form of dynamic NAT.  
Security NAT improves security because the IP addresses of the internal hosts are invisible. In PAT, the private address prevents the public address from being exposed.
Ports NAT uses no ports in the translation process. PAT uses source ports in the translation process.