Set aside how the two are made and look at what you end up with. Distilled water has essentially nothing dissolved in it and tastes flat. Reverse osmosis water is very low in dissolved solids but not empty, and most people find it tastes clean rather than blank. That difference decides which one you drink and which one you keep for the appliances.
Taste at the kitchen table
Dissolved minerals carry flavor, so water with almost none tastes noticeably flat, and distilled is the flatter of the two. Reverse osmosis output retains a small residual, and many systems offer a remineralisation cartridge that adds a measured amount back specifically to restore taste. Households that drink treated water all day usually prefer reverse osmosis for that reason, while a distiller more often ends up serving a specific job rather than the daily jug.
Appliances that want distilled specifically
Steam irons, humidifiers, CPAP machines, autoclaves and lead-acid batteries are the classic cases, and their manuals often name distilled water directly. The reason is scale: anything dissolved eventually deposits on a heating element or an emitter and clogs it. Reverse osmosis water is close enough for most of these in practice, but where a manufacturer's warranty specifies distilled, follow the manual rather than the argument, because the cost of being wrong lands on the appliance.
Cooking, coffee and ice
For cooking, either is fine and neither changes results much. For coffee and tea, a small mineral content actually helps extraction, so completely flat water tends to produce dull cups and many enthusiasts prefer reverse osmosis with remineralisation over distilled. For ice, the visible benefit of both is clarity, since the cloudiness in ordinary cubes is dissolved minerals coming out of solution as the water freezes.
Which to install rather than buy
If you need small volumes for appliances, buying distilled by the jug or running a countertop distiller occasionally is sensible. If your household wants treated water on tap all day, an under-sink reverse osmosis system is the better fit, because it delivers on demand and does not need someone to remember to start a batch. Our reverse osmosis buying guide covers stage counts, tank sizing and what the drain connection requires.
Questions people ask about distilled vs reverse osmosis water
Can I use reverse osmosis water in a steam iron?
Usually yes, because it is very low in dissolved solids, but follow the manual where the manufacturer specifically names distilled water.
Which tastes better?
Most people prefer reverse osmosis water, since a small residual mineral content keeps it tasting like water rather than tasting flat.
Do either of them make clear ice?
Both help, because cloudiness comes largely from dissolved minerals and trapped air, though freezing speed matters too.