breakfast cereal vs corn flakes

breakfast cereal

noun
  • A food made from processed grains, such as maize, oats, wheat or rice, usually eaten for breakfast with milk and sometimes sugar. 

corn flakes

noun
  • A breakfast cereal made from toasted flakes of maize. 

How often have the words breakfast cereal and corn flakes occurred in a corpus of books? (source: Google Ngram Viewer )