Both digital oscilloscopes and analog oscilloscopes may produce the above two kinds of graphs.

Digital oscilloscope recovers the original waveform after sampling through the processing of supplementary points and sampling points. There are few sampling points on the rising edge and falling edge, so the waveform you see seems to have no edges. In fact, after the expansion, there is. If the points are well supplemented, such as using the so-called sampling function of sin(x)/x, the effect will be better. You can see the edge.

If the intensity of glow is adjusted, the analog oscilloscope can realize two kinds of images.

The display of CRT is not necessarily an analog oscilloscope, but also an early digital oscilloscope. But now, very few. Almost all of them are TFT LCD.