All they have in common is the factory name and general quality. If I remember correctly the Zeiss 60mm has laser filters built in which typically degrade the picture quality to some extent giving it a yellowish or bluish tint but saves your eyes from military laser emitters.
The 85 has better optical clarity and picture quality but the 60mm versio is ruggerized for military use and has a reticle. You can not buy a reticle ocular for a 85 spotter. Basically you are comparing a military spotter to a high-end bird spotting scope. You can get better view quality but you will lose in ruggedness and general sniper usability if you choose the 60mm version.
My pick was/is Discope 65 (straight) with the 30X mildot ocular. You can not buy these brand new anymore and I suggest you take a look at the Leupold 16-40X60 spotter with the P4-reticle.