The first and most important of which is that the USA is a democracy with a free press. This allows the people of our country to ask almost any question we want of the powers that be, and gives us the oppurtunity to make significant changes in our government every two years. Unfortunately the same is not true in Iraq. Every news agency in Iraq is controlled by the government, and the only way Saddam will vacate his position is if he is forcibly removed.
Another important contrast is that we hold nuclear arms as a deterrence to keep other nations from firing their weapons at our country or our interests abroad. If Bush, or any other President, ever used even one nuclear weapon without severe provocation he might not last to lose his next election. Our congress would likely have him removed. Saddam has used his weapons against Kurds in his own country who probably don't have anything more powerful than some old tanks and artillery pieces, if that.
Saddam has compared himself to Saladin, a 12th century sultan who used military might to bring much of the Middle-East under his control. Saddam has tried to follow that example, first by intiating a war with the Iranians in 1979, and then by attempting to annex Kuwait. I think the overwhelming fear of western leaders and politicians is that he will use any major weapons he has to subjugate Israel and his other neighbors if those weapons are not removed.
Diomedes