IPV4 vs IPV6

Address Space
IPv4:4 Billion Addresses
IPv6:2^128
79 Octillion times the IPv4 address space

Configuration
IPv4: Manual or use DHCP
IPv6: Universal Plug and Play (UPnP) with or without DHCP
Lower Operation Expenses and reduce error

Broadcast / Multicast
IPv4: Uses both
IPv6: No broadcast and has different forms of multicast
Better bandwidth efficiency

Anycast support
IPv4: Not part of the original protocol
IPv6: Explicit support of anycast
Allows new applications in mobility, data center

Network Configuration
IPv4: Mostly manual and labor intensive
IPv6: Facilitate the re-numbering of hosts and routers
Lower operation expenses and facilitate migration

QoS support
IPv4: ToS using DIFFServ
IPv6: Flow classes and flow labels
More Granular control of QoS

Security
IPv4: Uses IPsec for Data packet protection
IPv6: IPsec becomes the key technology to protect data and control packets
Unified framework for security and more secure computing environment

Mobility
IPv4: Uses Mobile IPv4
IPv6: Mobile IPv6 provides fast handover, better router optimization and hierarchical mobility
Better efficiency and scalability; Work with latest 3G mobile technologies and beyond.