IPv6 changed some things. First and foremost it has a huge address space:
- IPv4: 4294967296 (2^32)
- IPv6: 340282366920938463463374607431768211456 (2^128)
Then they simplyfied some things:
- Removed Broadcast in favor of Multicast and Anycast
- Added autoconfiguration without a DHCP server
- Better subnetting support
And much more
I think Safari is WebKit.