Bush will be out of power in 2 years. Osama keeps running and running.
Bush's war places himself between warring sectarian violence: sunni vs shia, or Taliban vs northern alliance, or Kurds vs everyone else. Innocent people are killed unintentionally.
Osama targets innocent people because he intends to create chaos. His soldiers wear no uniforms, hides in mosques, and follow no rules.
Bush is an elected ruler of a country. Osama was not elected, runs no government, but would if he could.