Both. A lot of the smaller pitting, what you might get from sand or small gravel, can be removed by actually polishing away some of the glass. There is a technique to the polishing involved with the DA and specifically the 3M professional glass polisher used. (Amazon has it for around $70/liter.) A little goes a long way and the polish changes consistency as you go. It took me a while to get it down.

It also does give a super polish. Some of the deeper pits remain but they seem less noticeable and the small ones are gone which used to light up when the sun hit the windshield in a certain way.

 

Mine was pitted, too. The polish can only help so much. It's the star-like glare and reflection of oncoming traffic headlights that is hard to eliminate.