1a. Michael will be running a marathon this Saturday.
1b. Michael is running a marathon this Saturday.
2a. Michael will be DJing at the Manchester festival this Saturday.
2b. Michael is DJing at the Manchester festival this Saturday.
Is there a difference in the meaning between these forms (future continuous or present continuous)? All these sentences suppose that the event (marathon, festival) has been planned before (but is it always the case to use both forms). Are they employed interchangeably?
May be the future continuous is better as running marathon or DJing is a long activity, or may be in term of certainty present continuous is stronger than future continuous?