-Secretary of Defense
The Secretary of Defense is a very important person elected by the President with the approval of the Senate.  This is the guy that decides what our armed forces do when the President decides that we are at war and what he wants to do with them.  The Secretary of Defense just simply carries out those demands.  He is responsible for the formulation of general defense policy related to all matters of direct and primary concern to the Department of Defense.  He has a cucial job earning him $191, 300 per year.

-Secretary of Transportation
The Secretary of Transportation also plays an enormous role for our country as he or she is in charge of anything from laws regarding transportation to the roads that are built making the drives as safe as possible.  The Secretary of Transportation is 14th in line in the Presidential line of succession and his/her role is to develop and coordinate policies that will provide and efficient and economical national transportation system.

http://wiki.answers.com/Q/What_is_the_role_of_the_presidency

The president has many many many powers.  He can control anything as a commander in chief of the armed forces to enforcing that laws are carried out.  He/She can can also grant reprieves and pardons for federal offenses.

http://en.wikipedia.org/wiki/President_of_the_United_States

The President is the head of state and the head of government of the United States and is responsible for dictating the legislative agenda for his party.

http://www.c-spanclassroom.org/pdf/ws_rolesofthepresident.pdf

The President of the United States is the Party Leader, the Commander-in-Chief of the Armed forces, and the Chief Executive.