This is a very important issue, that most people seem to really miss understand. During a declaration of war the country is in a military state.
For example, my great grandfather owned thousands of acres of beach property in California that he was pumping oil out of before WWII. The oil tanks that the Japanese destroyed in California during the war he built with his own hands. He got a letter that the US government which stated they were taking the land and that was it, they kicked him out of his own home and never got it back. That is a delcoration of war.
The war against the terrorists doesnt need this great of government power to win.
Not necessarily. However in this instance, the 'war' was against another nation, namely Iraq and Afghanistan, in removing their current leadership. The same as with Korea and Vietnam. These actions were against a government and in none of the situations was war officially declared