| 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. |