A mobile workstation is a laptop geared towards professional productivity involving, for example, 3d modeling and video editing.
Workstation laptops are very adequate as they will feature higher-end hardware than most machines.
The first thing to look for in a mobile workstation is that the hardware will perform up to expectation in the applications you intend to use. Next, reliable battery life is essential. Lastly, consider the weight, and find something comfortable you can move around.