How is a waveform shown on the oscilloscope different from a compressional wave?

The waveform shown on an oscilloscope is a signal graph of voltage as a function of time.

Such a signal isn't considered by the oscilloscope to be traveling, and hence the oscilloscope itself doesn't see the signal as a wave.

In the wire though, it "sort of" is a longitudinal wave of electrons ... but then again, there is more to the story. There is also a radio EM wave in the surrounding electric and magnetic fields, and the engineers interested in long distance signal transmission study these fields to estimate velocity factor.