Sigma 30mm vs Zeiss 24mm

I think there's no doubt that a) the Sigma 30mm is phenomenal value for money, and that b) the Zeiss 24mm is the better lens. Whether the quality differential is worth it is a seperate discussion and an individual decision.

Aside for the f1.8 aperture, it comes down to color/contrast and quality of bokeh. So to answer your question, even outdoors in bright light at f8 I think you'd see a noticeable difference in those attributes.

The 50f18 is also a great lens, but it can be a bit narrow for indoor use, and I do find the color/contrast lacking relative to the Zeiss 24.