IPv4 and IPv6 are both protocols for identifying and communicating with devices on a network. IPv4 is the fourth version of the Internet Protocol, while IPv6 is the sixth version.
Main Differences
Address length
IPv4 uses 32-bit addresses, which limits the number of possible addresses to 2^32 or 4.3 billion. On the other hand, IPv6 uses 128-bit addresses, which allows for a much larger address space of 2^128 or approximately 3.4×10^38 addresses.
Address notation
IPv4 addresses are expressed in dotted decimal notation, which means that each byte of the address is separated by a period. For example, an IPv4 address might look like 192.168.1.1. IPv6 addresses are expressed in hexadecimal notation, which means that each 16-bit segment of the address is separated by a colon. For example, an IPv6 address might look like 2001:0db8:85a3:0000:0000:8a2e:0370:7334.
Security
IPv6 has built-in support for IPsec, which is a suite of protocols for securing Internet Protocol (IP) communications by encrypting and authenticating each IP packet. IPv4 also supports IPsec, but it is not built-in and requires additional configuration.
Routing
IPv6 has a simplified header format and removes some of the complexities of the IPv4 header, which can improve routing efficiency and reduce the processing overhead on routers.
Multicast
IPv6 has a more efficient and scalable method for multicasting, which allows packets to be sent to multiple destinations at once.
Compatibility
IPv4 is still widely used and supported, but it is running out of available addresses. IPv6 was developed to address this issue, but not all devices and networks are compatible with IPv6 yet.
Example
Let's say you want to connect to a website with the IPv4 address of 192.0.2.1. Your device will use the IPv4 protocol to send packets of data to that address and receive packets back.
Now let's say you want to connect to a website with the IPv6 address of 2001:0db8:85a3:0000:0000:8a2e:0370:7334. Your device will use the IPv6 protocol to send packets of data to that address and receive packets back.
In general, the differences between IPv4 and IPv6 are not something that most users will notice, as the protocols are largely transparent to end-users. However, network administrators and developers need to be aware of the differences when designing and implementing network infrastructure and applications.