I don't know about the specifics of the Rollei market but in large format lenses, Tessars are, generally speaking, older, command lower prices and are considerd to not perform as well as the (generally) newer Xenars. One way of understanding this is that Schneider "modernized" the basic 4/3 design. They made improvements in design, materials and manufacturing.

Personally, I greatly prefer the Xenars to the Tessars...