One president attended 2 of this nation's top universities, while the other had precious little formal education. The latter president, however, came to office infinitely better prepared to handle the tasks at hand. The latter president was much better informed about the critical issues of his time, and he had a vastly better ability to communicate his understanding of those issues.
The contrasting temperaments between the 2 men is also striking. Lincoln was willing to admit that he occasionally made mistakes. He was willing to reconsider previously-held positions in light of new events. He was willing to hear divergent points of view. W appears to hold a "somewhat" different perspective on all 3 of these subjects.
It's also fascinating to consider the differences between the difficulties that the 2 men faced in office. The current WH constantly claims that it has been presented w/ an unprecedented crisis that calls for it to assume unprecedented powers. Al Queda, however, has yet to place an army on the south bank of the Potomac. It has yet to recruit a large percentage of this country's military leadership to its cause. It has yet to establish a rival captial in Richmond.
As bad as W and his WH have been in absolute terms, they have been infinitely worse in relative terms when they are compared to the founding presidency of their party.