chili pepper vs red pepper

chili pepper

noun
  • Any fruit of a plant of the botanical genus Capsicum, which has a spicy/burning flavour because it contains capsaicin. (Not all chili peppers are particularly spicy, but all true chili peppers contain some capsaicin, in contrast to e.g. the bell pepper, which is not a true chili pepper and does not.) 

red pepper

noun
  • A red-colored, ripe, bell or sweet pepper. Unripe peppers of this variety are green and edible but not as sweet. 

  • Spicy pepper. 

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