The optics can all be manufacturered to the specs of the dealer so there will be variances as mentioned in glass quality, coatings, emitter programming, bodies etc. The largest difference most people will spot is the glass itself which has a huge range in costs and an area that many dealers will cut corners to reduce cost. We use the highest quality glass available with the best coating. We also have the optics programmed for competition use which optimizes brightness levels.
Also, there are chinese clones on the market that look like popular optics but do not have the same internals.