What is the difference between "future simple" and "futur proche"?

The "future simple" tense is used when one wants to describe an action that will take place sometime in the future. In English, we use "will" or "shall" + a main verb, for eg: I will go for a walk. In French, we do not use any auxiliary. We simply add the appropriate ending (ai, as, a, ons, ez, ont) to the infinitive of the verb, for eg: Je me promènerai.

The "futur proche" tense is used to describe an action that will happen in the near future. In English, we use the verb "to be" in the present tense + the present continuous form of "to go" + the main verb, for eg: I am going to go for a walk. In French, it is quite similar. We use the verb "to go" ("aller") in its present form, and the main verb in its infinitive form, for eg: Je vais aller me promener.