how is that different than a declaration?
It is a very specific and very detailed statement, and we have not declared a State of War since World War II.
Here is the Declaration of War against Germany from December 11, 1941:
Whereas the Government of Germany has formally declared war against the Government and the people of the United States of America:
Therefore be it
Resolved by the Senate and House of Representatives of the United States of America in Congress assembled, That the state of war between the United States and the Government of Germany which has thus been thrust upon the United States is hereby formally declared; and the President is hereby authorized and directed to employ the entire naval and military forces of the United States and the resources of the Government to carry on war against the Government of Germany; and, to bring the conflict to a successful termination, all of the resources of the country are hereby pledged by the Congress of the United States.