Simply, A decoder takes a scrambled or encrypted signal and decodes it. A demultiplexer is a device used to separate two or more signals that were previously combined by a compatible multiplexer and transmitted over a single channel.
Difference Between Demultiplexer & Decoder, Who Can Help?
A decoder rearranges a single signal into a more usable signal.
A de-multiplexer splits one compound signal into many signals.
A de-multiplexer splits one compound signal into many signals.