base camp vs campground

base camp

noun
  • An encampment used temporarily for storing supplies and preparing for a larger activity, such as mountain climbing or hunting. 

campground

noun
  • An area where a camp meeting (a retreat) is held. 

  • An area where tents are pitched. 

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