To put it in an easy way - IPv6 has the same IP addresses, but different ports. It also detects as unique different IPs by the controllers. IPv4 - different IPs, but the ports are the same, it depends on the protocol. By the way, IPv4 is suitable for almost all sites and programs, unlike the new IPv6. From here, you can check with which sites IPv6 will work or not. You can only use IPv4 proxy for online games.