Sure, sure - there are lots of ways to calculate the political differences between the two--you could point out, for example, that Obama tied for first among economical liberals in the Senate, while Brownback ranked as the 8th most conservative.
Being the economic conservative that he is, Brownback would surely like to know what the market thinks of the difference between him and Illinois's junior Senator.
And here's the answer...
Both Senators listed book advances on their recently filed disclosure statements:
Obama - $425,000 advance from Random House
Brownback - $15,000 advance from W Publishing Group
The difference: $410,000. Or put another way, Obama is worth about 27 times more.
The market has spoken.