What is MAC Address? 48 bits vs 64 bits ? mac address vs ip address

What is MAC Address :

The Media Access Control address is a binary number used to uniquely identification of the computer or other devices in the Network. It work on Data Link Layer of OSI model. Every communications devices like router server and switch has the MAC address sometime it called physical address.

48 Bits long MAC Address :

48 Bit MAC addresses are 12-digit (6 bytes or 48 bits) hexadecimal numbers.Pasted are the 48 bit MAC address and in the below example First 6 bytes are know as organizationally unique identifier (OUI) and the last 6 bytes are know as Network Interface Controller(NIC).
JJJ.JJJJ.KKK.LLL
UU-II-OO-PP-EE-DD
VV:GG:JJ:WW:MM:SS

64 bit MAC Address

Based on IEEE 802.15.4 we used the 64 bits MAC address instead of 48 bits. Pasted are the 64 bit MAC address and in the below example First 6 bytes are know as organizationally unique identifier (OUI) and next 4 bit are know as know Extended unique identified (EUI)  the last 6 bytes are know as Network Interface Controller(NIC).
VV:A2:JJ:MM:SS:23:45:65

MAC vs. IP Address Relationship:

TCP/IP networks use both MAC addresses and IP addresses but for separate purposes. A MAC address remains fixed to the device's hardware while the IP address for that same device can be changed depending on its TCP/IP network configuration.Media Access Control operates at Layer 2 of the OSI model while Internet Protocol operates at Layer 3. This allows MAC addressing to support other kinds of networks besides TCP/IP.