Difference between IPv4 and IPv6

                      IPv4                          IPv6
Internet protocol version 4 is a 32-bit IP address.Internet protocol version 4 is a 128-bit IP address.
The address space of the IPv4 address is 4.29 ×10^9.The address space of the IPv6 address is  3.4 x 10^38.
IPv4 is represented in decimal format.IPv6 is represented in hexadecimal format.
IPv4 consists of 4 octets where each octet ranges from 0 to 255 and is separated by period(.).IPv6  consists of 8 groups of 4 hexadecimal digits each group separated by a colon(:).
IPv4 header is 20-60 bytes.The IPv6 header is fixed at 40 bytes.
The transmission scheme in IPv4 is broadcasting.The transmission scheme in IPv6 is multicast and anycasting.
IPv4 supports VLSM(variable length subnet mask)IPv6 does not support VLSM.
IPv4 supports DHCP and manual address configuration.IPv6 supports autoconfiguration and renumbering configuration.
In IPv4 fragmentation is done by sending and forwarding routes.In IPv6 fragmentation is done only by the sender.
In IPv4 checksum field is available.In IPv6 checksum field is not available.
Encryption and authentication are not provided in IPv4.Encryption and authentication are provided in IPv6.
IPv4 uses ARP(Address Resolution Protocol) to map to MAC addresses.IPv6 uses NDP(Neighbor Discovery Protocol) to map to the MAC address.