Rifle Scopes Zeiss S5 vs the Zero Comp optics quality

A Zeiss S5 5- 25x56 mm is cheaper than a Zero Comp 5- 27x56 mm. Why is the glass on the Zeiss inferror ?
I think you’re just asking how the two scopes compare, and why the ZCO is more popular on this site, right? Because two scopes can have equal glass but other things, like turrets or reticles, can sway the market.
 
Take a look at Ilya Koshkin's, (aka Dark Lord of Optics) reviews.

The glass from all the top brands like ZCO and Zeiss will be pretty similar.

Pick the one with the reticle you prefer. None of the other features will make much of a difference. Unless you need the extra 5 mils of elevation and daylight bright reticle on the Zeiss.