MAC address/ physical address: Communicating nodes at physical and data link layers are identified by unique address known as MAC address. Every NIC of each communicating device will have unique mac address. Layer2 switches use MAC address for communication purpose.
IP address: Though MAC addresses are unique, they cannot be used for communication across the Internet. Thus for the purpose IP addresses are introduced. A communicating node must have atleast one public IP address to communicate on the internet. Currently there are two version of IP addresses i.e. IPv4 and IPv6. IPv4 addresses are4 byte in lenght while IPv6 are byte in length. IP address is used to reach the destination node's network layer. IP header consist of protocol type field to identity protocol (TCP, UDP, ICMP etc) used in communication. Port number is also used in communication at application layer to differentiate between different application layer protocol (HTTP, SMTP, FTP etc).
