RO and UV are like soap and bleach.

Soap does not clean anything, it simply removes the tensile strength of the water molecule which allows them to penetrate fabrics or hit particles much smaller than they could when they were clinging together. To see this, float a razor blade in a dish of water and add just one drop of dish soap..the blade sinks immediately.

Bleach is simply a disinfectant. Kills germs.

RO like soap, removes particles larger than the water molecule by hyper filtration.

UV simply disinfects then passes the water thru a filter.

RO is far superior for filtration as it lowers the TDS to almost zero.

Here are two links explaining both.....

UV...
http://www.excelwater.com/eng/b2c/water_tech_3.php

RO...
http://www.excelwater.com/eng/b2c/water_tech_4.php

GM