Once upon a time Google (NASDAQ:GOOG) (NASDAQ:GOOGL) was a search engine that charged for advertising based on clicks and Amazon (NASDAQ:AMZN) was an online retailer that made money on each transaction sold on its site. Today the lines distinguishing the tech giants' core businesses are blurring as they butt against each other, notably in product search. Eighty-eight percent of Google's 2014 revenues came from the bread-and-butter advertising business on owned and network sites. Sixty-eight percent of Amazon's 2014 revenues are from merchandise sales, compared with just a quarter from media, which includes advertising. Read more