Reverse Osmosis is filtered but in the final stage it's run through a DI anyways, RO water is far more pure then just DI, My RO water from my RO-Man has 0 TDS, Some say it absorbs mentals from the loop, IMO it's rubbish the more pure the water is the better, I use my RO unit because i have a Marine fishtank.
Reverse osmosis
Deionized
Distilled
The 3 main ones the top to bottom in TDS rating.