Multiplexing is the name given to the process of stuffing/switching/packing multiple signals, channel, bits, etc into a single stream/medium/band, whereas the opposite act of separating each individual packed signal, bit etc, back is named as de-multiplexing. In multiplexing each signal (or bits) remains completely **intact** and have no kind of intersignal interaction other than errors and ditortions whatsoever.

Convolution, on the other hand, operates on two signals and produces a **new** third signal which is somewhat like the child of the two parents. It's properties are related to its parents by the mathematics of the convolution process. Usually a convolution will be used to produce the output signal of LTI systems where the input signal is convolved with the system impulse response. Rarely a convolution between two arbitrary signals also considered (especially in frequency domain, which is more of a theoretical guide rather than a computational one, circular DFT convolution being an exception). The opposite operation of convolution is named as deconvolution and seeks for finding the driving input from a given output under different constraints.