President Bush did not present the Medal of Honor to the 29 Navajo code talkers honored back in 2001, but presented each with the Congressional Gold Medal, awarded by Congress to persons "who have performed an achievement that has an impact on American history and culture that is likely to be recognized as a major achievement in the recipient's field long after the achievement."
The Medal of Honor (not "Congressional") is awarded by the President in the name of Congress for "conspicuous gallantry and intrepidity at the risk of life above and beyond the call of duty." It is the highest combat award given in recognition of a specific act of bravery.