-or vs -th

-or

suffix
  • Creates an agent noun, often from a verb, indicating a person or object (often machines or parts of them) that do the verb or part of speech with which they are formed. 

  • Appended to the names of members of classes of components, especially those that have an extensive property name of the same root suffixed with -ance 

  • Used to form nouns of quality, state, or condition. 

-th

suffix
  • Used to form nouns from verbs of action. 

  • Used to form a term denoting the ordinal numeral corresponding to the value, being a natural number, of a mathematical expression. 

  • Used to form the ordinal numeral when the final term of the spelled number is not “first”, “second”, or “third”. 

How often have the words -or and -th occurred in a corpus of books? (source: Google Ngram Viewer )