hot pepper vs sweet pepper

hot pepper

noun
  • Any of the plants that bear such fruit, especially the species Capsicum annuum and Capsicum frutescens and their numerous subspecies, varieties, or cultivars. 

  • Any of various small peppers of highly notable pungency or heat. 

sweet pepper

noun
  • The fruit of a non-spicy cultivar of pepper, Capsicum annuum, marketed in green-, red-, yellow- and orange-skinned varieties. 

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