Simple Future and Future Progressive Tense

1.   Simple future tense

Often called will. because, the modal auxiliary verb in this sentence is will.

FORM :

(+) S + WILL + Verb1

ex: I will sing

(-) S+WILL+not+Verb1

ex: I will not sing

(?) will + S + Verb1

ex: Will she sing?

2. Future Progressive Tense

1. Form: WILL + BE + -ING VERB

The future progressive is formed by taking the modal will, the base form of the verb BE, and an action verb + -ING.

What about the other two future forms? We can never use be + -ing verb instead of will 

Example : (She will be eating dinner).

2. Use:

The function of the future progressive is to show a continuing (long) action getting interrupted by a short future action.

3. Time Marker:

The time marker when is common for this case.

4. Examples:

• I will be sleeping when you arrive home from work next Friday night.
• They will be doing presentations in class when the practice fire alarm rings at 2 p.m.
• The mayor will be finishing up her work when the power goes out at the scheduled time tomorrow.

Sources : https://www.ego4u.com/en/cram-up/grammar/prepersim-preperpro

 http://blog.esllibrary.com/2013/09/19/simple-future-vs-future-progressive/