Four things. The panel is 7-inch 9K (8520 × 4320) rather than 6.6-inch 4K (4098 × 2560). Speed is 150 mm/h rather than 70. Levelling is automatic rather than sensor-assisted manual. And the LCD is protected by 9H tempered glass rather than PET film. The build volume is slightly larger at 153 × 78 × 165 mm, and power-loss recovery is added.

Yes, on fine texture — chainmail, fabric folds, small facial features and engraved detail. On larger smooth surfaces the difference is marginal. The more consequential upgrade for most buyers is actually the speed: at 150 mm/h against 70, a tall plate finishes in less than half the time, which changes how much you can produce in a week.

The masking LCD is the most expensive consumable on any MSLA printer, and it fails from two causes: scratches during cleaning, and resin leaking through a punctured release film onto the panel. A tempered glass cover takes that damage instead of the screen, and it can be wiped firmly without risk. Over a machine's life it can be the difference between one LCD replacement and three.

Compare plate sizes rather than resolution. This gives 153 × 78 mm; a Saturn 4 gives 219 × 123 mm — roughly 2.2× the area, which matters far more than 9K versus 12K if you batch parts. Choose the Mars 5 Ultra if desk space is limited or your parts are small and detailed; choose a Saturn if you want to fill a plate and sell what comes off it.

The same as any resin printer, regardless of size — a compact machine does not mean a compact problem. Site it somewhere ventilated that you do not sleep in, ideally a garage, utility room or workshop with a window. Resin off-gasses during printing and IPA during washing, and a sealed room accumulates VOCs overnight. Enclosures and carbon filters reduce smell but not VOCs, and direct sunlight will partially cure resin sitting in the vat.