plodder vs worker

plodder

noun
  • A person who works slowly, making a great effort with little result; a person who studies laboriously. 

  • One who plods. 

worker

noun
  • A person who performs labor for a living, especially manual labor. 

  • A nonreproductive social insect, such as ant, bee, termite, or wasp. 

  • A female ant, bee, termite or wasp. 

  • A thread performing one instance of a particular task within a program. 

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