The document discusses the different uses of will and going to when expressing future tenses in English. Will is used to express decisions, predictions based on present assumptions, and promises or offers. Going to is used to express future plans and intentions, as well as predictions based on present evidence. Both can be used to talk about the future, with will implying more uncertainty and going to implying more certainty or intention. Time expressions like tomorrow, next week can be used with both will and going to when discussing future plans or predictions.