is v+ing to and will v to

The differences are subtle, and in most cases either one could be used. But here are some of the differences:

"He is going to New York next week."

In this sentence, the verb "to go" is in the present continuous tense, which emphasizes the immediacy of the action. The sentence is emphasizing WHEN he is going to New York.


"He will go to New York next week."

In this sentence, the verb "to go" is in the simple future tense, which emphasizes the action itself. The sentence is emphasizing WHAT he is doing next week.


If you were asked "When is he going to New York?", you would answer with the first sentence. If you were asked "What is he doing next week?", you would answer with the second sentence. But like I said, in spoken English the sentences mean almost the same thing; any English speaker would understand what you mean if you used one of them instead of the other.


By the way, if you have more questions about English grammar, I recommend posting them to this thread rather than starting a new one.