There are a hundred different (and contradictory) definitions of plot, so I’ll just use the most useful way to think about it.
If story is the effect that happens in our audiences’ brain, plot is the method and machinery that creates this effect. In a good story, this machinery is hidden, like the rocks beneath the rapids or the secret pocket in the magician’s sleeve. Plotting is the real work of storytellers who sweat over their craft; selection, deselection; focus; removing friction. Almost all our work is plotting.