difficult vs oppressive

difficult

adj
  • Hard to manage, uncooperative, troublesome. 

  • Hard, not easy, requiring much effort. 

oppressive

adj
  • Burdensome or difficult to bear. 

  • Hot and humid of the weather. 

  • Tyrannical or exercising unjust power. 

  • Weighing heavily on the spirit; intense, or overwhelming 

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