Wälzfräsen = hob(ing) see Wikipedia, Leo, etc.
https://dict.leo.org/englisch-deutsch/WälzfräsenWälzschleifen = generating grinding see Leo
Heike :hob grinding (ich bin mir nicht ganz sicher…)
Karen: generation grinding (Langenscheidt Fachwörterbuch Technik und angewandte Wissenschaften)
https://dict.leo.org/forum/viewUnsolvedquery.php?idThread=16...Wälzschleifen (von Zahnrädern) / grinding-generating n, gear grinding by generating
(Kučera, Dictionary of Exact Science and Technology)
Both processes use different tools and finish.
7 Grinding of Spur and Helical Gears (July/August 1992)
Grinding is a technique of finish-machining, utilizing an abrasive wheel. The rotating abrasive wheel, which id generally of special shape or form, when made to bear against a cylindrical shaped workpiece, …, will produce a precision spur or helical gear. In most instances the workpiece will already have gear teeth cut on it by a primary process, such as hobbing or shaping. There are essentially two techniques for grinding gears: form and generation.
https://www.geartechnology.com/subjects/generating_grinding/