A packet and a frame are both packages of data moving through a network.

A packet exists at Layer 3 of the OSI Model, whereas a frame exists at Layer 2 of the OSI Model.

Layer 2 is the Data Link Layer. The best known Data Link Layer protocol is Ethernet.

Layer 3 is the Network Layer. The best know Network Layer protocol is IP (Internet Protocol).

To move through a network, a packet is encapsulated into one or more frames, depending upon the MTU size.