specialist vs specializer

specialist

noun
  • Someone who is an expert in, or devoted to, some specific branch of study or research. 

  • A stenotopic species. 

  • A physician whose practice is limited to a particular branch of medicine or surgery. 

  • Any of several non-commissioned ranks corresponding to that of corporal. 

  • An organism that is specialized for a particular environment. 

adj
  • Specialised, involving detailed knowledge of a restricted topic. 

specializer

noun
  • One who, or that which, specializes. 

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