Google Maps uses the same searches for businesses as Mapquest and other similar services. They all use engines like citysearch, superpages, dexknows etc.. So while different map services will come up with varying results, none of them are any more accurate than the others.
That's why I prefer to use an app that uses specific search engines that I find reliable (I use superpages via the Poynt app) when searching for businesses where I don't yet know very specific info. (ie, Pizza, Electronics Store, Grocery Stores)
I tend to save google searches for more specific locations (ie, specificly known addresses, Best Buy in Aurora CO, Coor's Field, Wrigley Field, Empire State Building, etc..).