shall and will

PLease tell me what is the difference between:

  1. ‘shall be able’ and ‘will be able’
  2. ‘shall have to’ and ‘will have to’

Is there any general difference between 'shall and ‘will’? - Maybe this fact, that ‘shall’ we should ONLY? use for persons : ‘I’ and ‘we’ and 'will for every person/persons?

Thank You :slight_smile:

This is such a frequently asked question, it might be best if you browse through … +and+shall and then ask any follow-up questions here.