conscientious vs principled

conscientious

adj
  • Influenced by conscience; governed by a strict regard to the dictates of conscience, or by the known or supposed rules of right and wrong (said of a person). 

  • Thorough, careful, or vigilant in one’s task performance. 

principled

adj
  • strongly adhering to, or heedful of, guiding beliefs or moral rules 

  • Based on, having, or manifesting principles 

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