Typically Shimano retains much of the basic design across a range of same component "levels". So the leverage of a XTR might very well be the same as the low cost Acera brake system. But the materials, finishing, weight AND marketing will all be at a more refined level on the pricier XTR grade. Pad materials could have greater friction or longer wear on either grade, springs and other steel hardware might be SS or chrome plated instead of black oxided. AL parts might be anodized with laser etched graphics instead of powder coated and adhesive backed foil decals.


But I'm not going to spend the time to dig into the published info to be more specific. Andy