Diferentiae or Differentiae: How To spell?
The word Diferentiae is misspelled against Differentiae, which is plural of "Differentia"
Differentiae has double "ff" is mispronounced as "f"Remember double 'FF' in between the strings Di & erentiae which should not be misspelled with single 'F'
Wrong Spelling:  Di-f-erentiae  Correct Spelling:  Di-ff-erentiae 
Find more wrongly spelled words of Differentiae to spell it well.