What are the key differences between a protocol and an interface?

Answer 1

Say there are 2 people who wish to communicate with each other.
Protocol would be the language they speak.
Interface is just that. Is it over the phone, over the net, over the air?

Answer 2

A Protocol is a set of rules used in an environment. An interface is hardware or software that bridges two environments that have different Protocols.

Answer 3

Depends on what on earth you are talking about. Lemme assume it is something to do with computers. I, personally, would use the term "interface" to indicate the lowest level of a communication interface (or control/instrumentation interface). The connector types, cable types, signal to pin assignments, signal levels and meanings. The issue of protocol is: now that you can electrically talk, how do you carry on a conversation? Example might be your printer. Now that you have cabled it up (the interface) you have to say something intelligent to make something happen. Like: Printer report your status, Printer clear your state to initial, Printer assume paper is letter size, Printer set to to top of page, Printer print the following text. If you have a scanner, you can imagine other conversations. And each "conversation" has a protocol of who says what and in what order. The above protocol would be correct for a printer to set up and print a line of text at the top of a page.