What is the difference between IPv4 and IPv6?
IPv6 or IP version 6 is the next generation Internet protocol which will eventually replace the current protocol IPv4.
The primary difference is that IPv6 uses 128 bit addresses as compared to the 32 bit addresses used with IPv4. This means that there are more available IP addresses using IPv6 than are available with IPv4 alone.
For a very clear comparison, in IPv4 there is a total of 4,294,967,296 IP addresses. With IPv6, there is a total of 18,446,744,073,709,551,616 IP addresses in a single /64 allocation.
To also help illustrate the sheer magnitude of available IP addresses using IPv6, you can get 65536 /64 allocations out of a single /48, and then 65536 /48 allocations out of a single /32. Many Service Providers are getting /32 allocations from their Regional Internet Registry (RIR) like ARIN, APNIC, RIPE, etc.