Best Practice for Job Titles

Summary

What is a best practice when defining job titles? Generic or Specific?

Content

Should a job title be created specifically as "Sales Representative - Wholesale", "Sales Representative - Retail", etc. or setup generic as "Sales Representative".  If generic as "Sales Representative" do you use the same job code for multiple employees or would you have multiple job codes? With either one job code or multiple how would you/where would you define the uniqueness?  Call it "area of responsibility" or something.  I also wonder what the intent was for the Business/Assignment Title vs Job Title is on the employment page.