Sorry I should have clarified. This is kind of tough to explain, and I didn't really understand it when I first learnt it either. When I say wider I'm talking about the stereo field of the mix. The crux of this is essentially panning and volume, but it also covers more complicated stuff such as the mid-side technique. Good use of the full stereo field is like the difference between a photo of a landscape and actually seeing it. Everything has depth and you can see (hear) where everything sits in relation to each other.
That being said I don't want to turn this thread into an explanation of terminology, so perhaps it might be a good idea to check out the guides and tutorials section or post some questions in the music production forum.
In regards to what Snow said, I haven't used Mixcraft before so I don't know my way around it. To top it off, I don't deal with strings very often! I'll let him come back and clarify his points as it sounds like he knows what he's talking about.