Wikipedia Defines Internet Protocol Address as:
An Internet Protocol address (IP address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing. Its role has been characterized as follows: “A name indicates what we seek. An address indicates where it is. A route indicates how to get there.”
The designers of the Internet Protocol defined an IP address as a 32-bit number and this system, known as Internet Protocol Version 4 (IPv4), is still in use today. However, due to the enormous growth of the Internet and the predicted depletion of available addresses, a new addressing system (IPv6), using 128 bits for the address, was developed in 1995, standardized as RFC 2460 in 1998,and is being deployed worldwide since the mid-2000s. [i]
As a summary:
1. An IPv6 address consists of 128 bits, while an IPv4 address consists of only 32.
2. IPv6 has a lot more usable addresses compared to IPv4.
3. IPv6 makes the router’s task more simple compared to IPv4.
4. IPv6 is better suited to mobile networks than IPv4.
5. IPv6 addresses are represented in a hexadecimal, colon-separated notation, while IPv4 address use the dot-decimal notation.
6. IPv6 allows for bigger payloads than what is allowed in IPv4.
7. IPv6 is used by less than 1% of the networks, while IPv4 is still in use by the remaining 99%.[ii]
Table of Differences:[iii]
|Addresses are 32 bits (4 bytes) in length.||Addresses are 128 bits (16 bytes) in length|
|Address (A) resource records in DNS to map host names to IPv4 addresses.||Address (AAAA) resource records in DNS to map host names to IPv6 addresses.|
|Pointer (PTR) resource records in the IN-ADDR.ARPA DNS domain to map IPv4 addresses to host names.||Pointer (PTR) resource records in the IP6.ARPA DNS domain to map IPv6 addresses to host names.|
|IPSec is optional and should be supported externally||IPSec support is not optional|
|Header does not identify packet flow for QoS handling by routers||Header contains Flow Label field, which Identifies packet flow for QoS handling by router.|
|Both routers and the sending host fragment packets.||Routers do not support packet fragmentation. Sending host fragments packets|
|Header includes a checksum.||Header does not include a checksum.|
|Header includes options.||Optional data is supported as extension headers.|
|ARP uses broadcast ARP request to resolve IP to MAC/Hardware address.||Multicast Neighbor Solicitation messages resolve IP addresses to MAC addresses.|
|Internet Group Management Protocol (IGMP) manages membership in local subnet groups.||Multicast Listener Discovery (MLD) messages manage membership in local subnet groups.|
|Broadcast addresses are used to send traffic to all nodes on a subnet.||IPv6 uses a link-local scope all-nodes multicast address.|
|Configured either manually or through DHCP.||Does not require manual configuration or DHCP.|
|Must support a 576-byte packet size (possibly fragmented).||Must support a 1280-byte packet size (without fragmentation).|
[ii] Read more: Difference Between IPv4 and IPv6 | Difference Between | IPv4 vs IPv6 http://www.differencebetween.net/technology/internet/difference-between-ipv4-and-ipv6/#ixzz1T6bnKJW