Wg mnie to bardzo trudne pytanie i pewnie jak zwykle wiele zależało od nawyków piszącego.
Tu masz ówczesne terminy stosowane wobec różnej maści młynarzy:
1) location: T(h)almüller (miller in the valley), Bergmüller (miller at or on top of a hill), Ober- and Mittelmüller (the miller at the upper and middle mill), Unter- or Niedermüller (the miller lower mill); in church books you can also find Müller der Obermühle (miller at the upper mill), etc.;
2) technique: Windmüller (windmill operator); Wassermüller, Wasserwieger (water-mill operator);
3) product: Bokemüller, Flachsmüller (flax miller); Ölmüller, Olmacher, Ölmann, Öhler, Öhlmann, Ölstampfer, Ölschläger, Olearius, Oehlstöter, Ölstößer (oil); Kornmüller, Brotmüller (grain miller); Bohlenschneider, Bortschnitter, Bredtschneider, Bretmüller, Brettmüller, Brettsäger, Brettschneider, Holzmüller, Sägemüller, Sageter, Sagenschneider, Holtschneider, Holzschneider, Holtsnider, Säger (sawyer of timber, lumber); Avenaticus, Gortemaker, Grutarius, Grützmacher, Grützmahler, Gruttemaker (groats, whole-corn, wholewheat); Malzmüller (malt); Waidmüller (plants for dying); Krätzmüller (metal waste); Drahtmüller (wire); Malzmüller (maltster, see Bierbrauer); Lohmüller (see Gerber - tanner); Amidammaker, Amidammacher, Ahmdammacher, Amidamfabrikant (cornstarch, cornflour);
4) from the old German term quirne, kürne (handmill, treadmill, later also used for water mill): Querner, Kirner, Kürner;
5) other terms: Aussacker, Bescheider, Molendarius, Molitor, Metzner, Mühlenbursche, Müllerknappe (helper at a mill); Mülscher, Müllergeselle (apprentice of the miller); Mühlenbereiter (official supervising mills); Mühlerbe (mill owner); Müllermeister (master miller); Bannmüller, Bestandmüller
http://www.european-roots.com/german_prof.htm