alt Hacker NewsAt the basic job of showing a normal 24bpp photo on screen, the differences between the formats are marginal.
jxl shines when you want to do anything even a little bit more complex. Support for lots more color formats, including fp ones. Support for an image with parts of it encoded losslessly, and parts with a lossy encoder. Great progressive decoding. And many more features.
The part of jpeg-xl I'm most excited for is when the 3d community starts standardizing the extra channels for depth maps, bump maps, roughness etc in the extra channels. You can use a single jpeg-xl as a full material system with progressive decoding for LOD and all the rest.