MAC addresses travel like a relay race while IP addresses travel like a marathon runner.
The MAC address is the permanent address of the Network Interface Card. It is normally exchanged among the switches for local communications.
The IP address is a temporary address assigned to any device, for communicating through the Internet. It is mostly handled by Routers, for long distance communications.
Now, for a long route packet transfer, the MAC address will keep changing from network to network. During each network, the packet will be handled by different MAC addresses, and be assigned the destination address of some local machine for the time being. While, the source and destination IP address will remain original.