Is there a fundamental difference in the lens material that causes this? I know very little about scopes. And what magnification constitutes long range vs medium range?
Long range scopes have better zoom (can see far away targets clearly), but have a scope glint which allows other players to spot you easily.
Medium scopes are not that zoomed in (you will mostly see just dots moving very far away), but has the advantage of not having scope glints meaning it will be very difficult for other players to spot you if you position yourself correctly.