Structure: Subject+will/won't+base form of the verb

Examples:

I will call my grandparents this weeknd. (instant decision)

She won't finish her work before the deadline. (prediction based on opinion)

I'll help you with those bags! (offer)

Be Going To

Uses: The "Be going to" structure is used to express plans, intentions, and predictions based on present evidence or intention

Structure: Subject+am/is/are+going to+ base form of the verb

Examples:

He's going to do exercise tomorrow morning (intention)

We are going to start a new project next month (plan)

Look at those clouds! I think it's going to rain (prediction based on evidence)

Negative: Subject + (am/is/are) + going to+ V

Question: am/is/are + subject + going to + V + ?