UI is User Interface & UX is User Experience. When we do design of interface, we need to keep in mind the usability aspects and how the end user will benefit from such a design.
There are several parameters by which a design is treated as a good design and it has very little to do with colors and visual being used.
Google has its own parameters, Microsoft does and so does Yahoo, they have even published them as guidelines.
We work on your software applications, websites and mobile apps to get the best user interactions design possible.