The margins of the oil business are obviously lower, but look at Exxon's revenue number. Around the world, people handed Exxon nearly $100 billion dollars in a single three-month period. Apple would have to sell 184 million of the cheapest iPad to hit Exxon's number.
(Side note: Excel 2008 is driving me nuts. Why did they make it so hard to label the axes? Why do attempts to make spreadsheet software easier to work with always result in greater complexity?)