What are the salient matters contained in an engagement letter in comparison to standard business contract?

The following are main areas covered in an engagement letter.

• Scope of the function.
• Time frame.
• Financial compensation.
• Obligation specified to each party etc.

I think it is very general question . Thank you for the invitation .

Most of the important issues to be stated clearly to avoid any future misunderstanding or stopping of the business are ;

1- The exact needed subjects from making the new contract

2- The role of every party

3- The amount of financial obligations for both of them

4- The exact date of the process and the progress plan needed

5- The date of closing the contract

6- The obligation of every party  to do in case of any delay or executed jobs, if any.

Thank you.