Premium vinyl awning fabrics come in brighter, more vibrant colors and they do make your RV look sharp.
There is also a small difference in the thickness of the vinyl. Standard vinyl is 13 mil thick and premium fabrics are 15 mil.
Awning manufacturers are limited in the thickness of material they use, so 15 mil is the thickest fabric you can get. If a thicker fabric was used, it would not roll up properly or fit in the roller or awning rail channels on your motorhome or travel trailer.