An order of magnitude is an observation/measurement/approximation that one thing is about 10 times bigger than another thing. It's an exponential thing, so 2 orders of magnitude means that Thing A is about 100x better or bigger than Thing B. Not 2 times. Not 20 times. If Citigroup has $500 billion in crappy loans on its balance sheet, and Bank of America has $50 billion in crappy loans, Citi's crappy loan exposure is an order of magnitude greater than BofA's.
Order of magnitude is not a general observation about size. Consider the following financial media conversation:
Interviewer: How would you estimate Apple's exposure to the Circuit City bankruptcy?
Financial Professional: In terms of order of magnitude, Apple's Circuit Citty receivables are about $200 million.
That's just wrong. Saying "order of magnitude" rather than "size" or some other noun may sound more intelligent, but since it's totally incorrect, it's not.