Shall and will have the same meaning but are used in different grammatical context. In British English, shall is used for first person and will is used for 2nd person or 3rd person.
In American English, shall is not used very often. Will is used instead, especially in its shortened form. For example, I'll see you tomorrow.
"Shall" is a formal way to express intended future action. The traditional rule is that to express a simple future tense shall is used after I (I shall leave at noon) and will in other cases, (Will you leave at noon?).
"Will" (in its verb form) is used to indicate future action for second or third-person (you, they).