according to my knowledge and all checks on the net, Applikatur and Fingersatz are normally used interchangeably. The only different usage I found is "Fingersatz" as "fingering" and "Applikatur" as "position" (on string instruments). But this meaning was only found in one context:

SCHOEN,M. Lehrgang für den Violin-Unterricht Op.38:XI (Nowotny). Applikaturen (4-7 Position). UE 1811. 20s. 75
http://www.svaf.se/enhorning/Viskol.htm

Since there really is no difference between the two terms and "Fingersatz" for string instruments tells you only the fingers to use and not the actual position (the player has to figure that one out him/herself, unless maybe it's a beginner's instruction book-in which case it would not be an Uretxt), I would just use Fingersatz (fingering) and basically ignore Applikatur unless the music in question is actually for string instruments.

Eine Applikatur (Fingersatz) die auch für kleinere Hände einfach zu
handhaben ist.
www.saxshop.nl/home-d.htm

Der Fingersatz (engl. fingerring) wird auch als Applikatur bezeichnet.
www.renesenn.de/the-fing.htm

Wenngleich Beethoven also mitunter die »falsche Applikatur« (d. h. einen unpassenden und damit weniger schön klingenden Fingersatz) wählte, so scheint er von seinen Violinsonaten vollkommen überzeugt gewesen zu sein
http://www.deutschegrammophon.com/special/insighttext.htms?I...