Both IPv4 and IPv6 are Internet Protocols that specify the format of the Internet packet (message). IPv6 is the sixth and the newest version of the protocol. The biggest difference is that IPv6 addresses are 128-bit IP address written in hexadecimal and separated by colons, while IPv4 addresses are 32-bit IP addresses. Regarding the unicast loopback address,which sends outgoing signals back to the same computer and is mainly used for testing:
The IPv6 unicast loopback address ( 0:0:0:0:0:0:0:1) is equivalent to the IPv4 loopback address (127.0.0.1).
