Difference between an IP and MAC address

For any packet we attach the source and destination Internet Protocol (IPv4). This packet may need to travel through many different networks. For each different network it will get a new layer 2 header with the MAC address of the router it entered the network on and the router it needs to leave the network on.

MAC address are really only there for a single network hop whereas the Internet Protocol (IPv4) is there for the whole journey.