Short Answer: They're exactly the same, although "will" is more common. Long Answer: In Early Modern English, only "shall" was used for the future tense and "will" meant "to want". Now they mean the same thing and the only difference is that "shall" is more old-fashioned. You usually only hear "shall" used in poetic speech nowadays. "Shall" is most commonly used to sound charming in a romantic context ex. "Shall we dance?" (Ie. "If you want to dance, it WILL happen, and vice-versa"). This has lead to the myth that "shall" is only used in the first or third person, but you can use "shall" any time you could use "will"; it might sound like you're reciting poetry though! You can hear "shall" in movies all the time. This is done for effect: it can make a character sound more authoritative, more formal, more ancient (particularly in fantasy or sci-fi films) etc.

If your English level is beyond intermediate, you do need to know a clear difference. Aside from practical uses, "will" relates to volition and "shall" relates to obligation (which is why you see "shall" so often in contracts).

Grammar Girl explains this well :) http://www.quickanddirtytips.com/education/grammar/shall-versus-will

yeah... "shall" isn't very common anymore but it can still be used. If it is put at the beginning of a sentence like, "Shall we go?" or "Shall we do this?" It is a more polite way of asking to do something. If it is used to express something you would do like "I shall go" or "I shall do this" then it is interchangeable with "will". I hope this was helpful! good luck^^

In modern speech, "shall" is rarely used, especially rarely in American English, where it's limited to such uncommon usages as interrogative suggestions, e.g. "Let's go, shall we?"