backpacking vs trek

backpacking

noun
  • low-cost, generally urban, travel with minimal luggage and frugal accommodations. 

  • hiking and camping overnight in backcountry with one's gear carried in a backpack. 

trek

noun
  • A slow or difficult journey. 

  • A journey by ox wagon. 

  • The Boer migration of 1835-1837. 

  • A long walk. 

verb
  • To travel by ox wagon. 

  • To travel by walking. 

  • To journey on foot, especially to hike through mountainous areas. 

  • To make a slow or arduous journey. 

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