danger vs difficulty

danger

noun
  • Exposure to likely harm; peril. 

  • An instance or cause of likely harm. 

  • The stop indication of a signal (usually in the phrase "at danger"). 

difficulty

noun
  • Physical danger from the environment, especially with risk of drowning 

  • An obstacle that hinders achievement of a goal. 

  • The state of being difficult, or hard to do. 

  • An objection. 

  • An awkward situation or quarrel. 

  • That which cannot be easily understood or believed. 

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