Now, keep in mind that this is all second hand information from me but I generally like to relate it to a computer or some kind of tech. If depression is the case where there is too much emotional strain inputted into the system until it collapses, then mania is the systems breaks failing (like a fan that keeps on whirring even when you're tell it to shut down). I've heard that people who are manic can go weeks without sleep and that in and of itself can destroy you pretty fast. I'm sure someone with bipolar can give you a much better description. I won't compare the 2 but I will say that I've heard the movement from depression to mania in people with bipolar is apparently very addictive. Which I can totally imagine is true.

In the end, both are pretty bad when you draw the bottom line but the grass sure does look greener from here huh?