What is a difference between the president’s formal and informal powers?

Formal powers are listed in the Constitution, while informal powers are not.
Formal powers are created in the executive branch, while informal powers are not.
Formal powers are created by Congress, while informal powers are not.
Formal powers are changed over time, while informal powers cannot be changed.

Formal powers are listed in the Constitution, while informal powers are not.

Explanation:

One example of president's formal power is the power to be Commander in chief of the military. This power is directly written under the Article II Section 2 of the U.S. Constitution,

One example of the president's informal power is conducting foreign policy initiatives. Even though this power is not directly written in the constitution, leaders of the foreign country know that they have to talk to the president if they want to strike a  deal with united states.