Amazon Web Services, Microsoft Azure, and Google Cloud Platform dominate the U.S. public cloud market, withOracle knocking on the door. But the data are obfuscated by definitions that can make comparisons among them almost impossible.Amazon has the clearest story: AWS had net sales of $12.7 billion in the fourth quarter, and $45.4 billion for all of 2020. Sales were up 28% for the quarter, and 30% for the full year.Oracle’s approach isn’t any better. Most of its corporate revenue, including clou