Luyện ngữ pháp - Destination B2 ((Unit 5: Grammar - Future time / present tenses in time clauses / prepositions of time and place))
There is sometimes little difference in meaning between will and be going to. It is often just a matter of formality. Will is generally more formal than be going to.
Sometimes it is more appropriate to use will rather than be going to.
Sometimes it is more appropriate to use be going to rather than will.