Before going any further, its necessary to clarify the difference between these two engagements. Learning is more self-explanatory: The pursuit of knowledge and skill. Earning, on the other hand, is more abstract. In my effort to be both general and specific, I have concluded that earning is the application of knowledge to pursue financial ends.
I did not attach this term to a measurable return on money because it not realistic to think that ALL activities under the earn umbrella will be directly related to a dollar amount. Some earning activities are less measurable than others, but the common denominator is action clearly related to a financial reward in the short term. I emphasize short term because this same definition in a long term context I would consider learning.
NOTE to the devils advocate: If the intention of the action is to earn, but the financial reward fails to transpire, the action, in my book, can still be considered one of earning. But lets avoid becoming overly particular here.
Okay, moving on