Quick take
RO is usually more practical for daily household drinking water because it is faster and less energy-intensive. Distillation remains useful for small-volume specialty uses.
Treatment mechanism
Distillation boils water and condenses the vapor. RO forces water through a semipermeable membrane. Both can reduce many dissolved contaminants, though volatile compounds require special consideration in distillation.
Energy and speed
Distillers are slow and electrically intensive because every liter must be boiled. RO produces water faster and can be more practical at household scale.
Mineral content and taste
Both methods can produce very low-mineral water. Some users prefer remineralization for taste, especially with RO systems.