The UTQG ratings are not based on any national standard. They tend to vary by manufacturer, and really only estimate the life expectancy of that manufacturer's tread versus their interpretation of other treadwear ratings in the marketplace. A lower UTQG rating only signifies that treadwear for that manufacturer is lower than other treadlife expectancies in the marketplace. It does not signify specific roadholding characteristics.
However, a lower UTQG rating generally is assigned to tires which are softer and "stickier" compounds that tend to allow higher roadholding characteristics. MAny high performance Summer only tires tend to fit this bill. My experience with many tires, only a few tires allow decent combinations of higher wear ratings and good road holding features, but these tend to be more expensive tires, and are rarely suited for cold conditions. Exceptions - Michellin Super Sports, or PS3, and surprisingly the Hankook Evo 12 fits this well. I have found many high performance tires that wear better and outhandle the OEM tires. Pirelli P7, Michellin PS2 A/S, Nitto Innova, and more. YMMV