guarded vs watchful

guarded

adj
  • Watched over; supervised. 

  • Cautious; restrained. 

  • When the practitioner formulating the opinion does not have enough information to know, or to foretell, what the outcome may be. 

watchful

adj
  • Fully observant, vigilant, or aware. 

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