In this context there is no perceptible difference between the two alternatives. You're right, they're pretty much the same. In other contexts, #2 suggests a *probability* of leaving that can be dependent on a condition. For example, "I'll be leaving soon unless they clean my hotel room". In a sentence such as the one I have given, you'd still hear native English speakers using #1 but #2 is preferable. I hope this helps you a little bit. Take care and good luck!

There is no difference in meaning, both are same. These two are just different ways, different sentence structure. Thanks!

i feel that it have no diffence

Here there is no difference.