A good rule of thumb is that lower mash temperatures favor a thinner, drier, beer that finishes with a lower FG while a warmer mash temp favors a fuller bodied beer that finishes with a higher FG.
A lower mash temp would be 147-150, while a higher mash temp would be 155-158. In the middle would be a medium bodied beer with an average FG.
Of course grainbill plays a huge part, as does the yeast strain.
But say you had a grainbill of 10 pounds base malt, and 1 pound of crystal. Using the same yeast strain, and everything else being the same, you could expect some differences.
For example, in my system, here's what I'd expect to happen.
At a mash temp of 147, I'd expect a thin bodied beer with a crisp finish and it to finish at 1.007-1.009.
At a mash temp of 150-152, I'd expect a medium bodied beer with a FG of 1.010-1.014.
At a mash temp of 155-158, I'd expect a fuller bodied beer with a FG of 1.016-1.020.
In other words, you can use the mash temperature to manipulate the body and amount of residual sugars in the mash. That means that you can make a Belgian finish light and crisp at under 1.010, by mashing under 150 degrees. That's pretty typical, and that's what I'd do.