There is a difference, easily demonstrable by an a/b comparison using a pair of oscilliscopes. By definition, a digital waveform is a series of finite steps, not a smooth curve. Just as in integral calculus, the goal is to obtain an infinitely large set of infinitely small variations. However, the experts tell us that beyond a certain point the human ear and human mind cannot notice an identifiable difference.
If you can see the steps on an oscilloscope on the analog output of a properly designed digital to analog converter, it isn't properly designed. The "reconstruction filter" on the output is defined and will not show the steps. This is brother Nyquist.
This is debated ad nauseam on the Pro-Audio list, and I'm not trying to bring that discussion here, but you shouldn't be able to see the difference on an oscilloscope or hear the difference.