Milled Glass and Glass Fiber

I am trying to determine the differences between two products, one containing milled glass, the other contains glass fibers. This material is to replace our current bobbins supplier for our sensors. The terms milled glass and glass fiber is what I am having difficulty defining. I am waiting to hear back from Sabic, the manufacturer, with their responce and I searched a bit on Engineers Edge and did not find anything. Just wondering if anyone had a simply answer.

Milled glass is a product usually supplied as fine pieces, grit or even powder fro mixing into resins and other engineered materials. Glass fiber is supplied as a string or small diameter "fiber".