Simplistically speaking, depression is a big recession, and the word 'big' is flexible.

>No, not even a recession according to The National Bureau of Economic Research:
>
>http://www.usatoday.com/money/economy/2008-11-03-economy-depression-recession_N.htm
>
>Compared to the Great Depression:
>
>Our economic woes dwindle in comparison. As of the end of June, the latest data available, the nation's gross domestic product was still growing at a respectable 2.8% rate. In the third quarter, it fell at an annual 0.3% rate. Unemployment in September was 6.1%. "We're a long way from the D-word," says David Wyss, chief economist for Standard & Poor's. "It's a recession."
>
>And, in fact, it's not even officially a recession. The National Bureau of Economic Research, the official arbiter of when recessions begin and end, has yet to declare the end of the most recent economic recovery. Even the shorthand version of recession — two consecutive quarters of shrinking gross domestic product — hasn't happened yet.
>
>Not in a recession? Could've fooled me...
>
>And why did the Great Depression last so long? According to these guys, it was all the fault of FDR:
>
>http://newsroom.ucla.edu/portal/ucla/FDR-s-Policies-Prolonged-Depression-5409.aspx