will or going to. Please help me

is this sentence right?

  1. “I am going to visit Hanoi this summer vacation” or “I will visit Hanoi this summer vacation”.

English has no future tense and so has to use other devices to express a future ‘idea’. The modals ‘shall/will’ and ‘going to’ are two examples of these devices. There is a slight difference in meaning between the two. ‘Going to’ suggests intention and ‘will’ (stronger in meaning) suggests either wish or determination to do something but both are perfectly acceptable as you have used them in your sentences.