"I'm going to spain " is in present tense and it means that you are on your way to Spain. " I will go to spain " in is future tense and it means that in future you will go to spain

"I'm going to Spain" does not always mean you are on your way there. It means you will go soon, and that you have already made plans. "I will go to Spain" means someday, maybe in ten years, but you have not actually made plans to do it.

As Prashant says: "I'm going to spain" is in present tense and it means that you are on your way to Spain. so in this sentence you can add a date/day/month or year to make it clear that when you are going there :)) Like this >>> I am going to spain this january. (it means you will go in january) As Prashant says: " I will go to spain " in is future tense and it means that in future you will go to spain.

Both indicate that you will be traveling to Spain some time in the future. However, the first sentence (I'm going to Spain) implies that it is going to happen relatively soon. (I'm going to Spain tomorrow. I'm going to Spain next month. You can even say "I'm going to Spain next year.") However, "I'm going to Spain in 2020" starts to sound a little weird without further context. "I will go to Spain," however, implies that is going to happen in the indefinite future. "Someday, I will go to Spain" sounds perfectly natural. "I will go to Spain tomorrow" sounds weird out of the blue and requires some background context. In sum, the two both indicate an action in the future, with a different emphasis on the immediacy of the time of the event.