The “going to” tense is used when the speaker refers to plans stated before of the moment of speaking. There are some differences between will and going to. The former is used when the speaker makes instant decision about the feature(example: I will drink a coffee with my friend) or he or she wants to imagine how the near future will be (example: In 4 years, I will be married).On the other hand, the latter refers to very well arranged plans (example: Next summer, we are going to the beach and we are going to stay in Maintains Hotel).