How long will it take for single gap to close with braces? Invisalign? (photo)

I have a gap between my front teeth. I was told my my orthodontist that all my teeth are perfectly straight and spaced aside from the on big one in the front top row. So I have two questions. A). How long will it take to close the top gap with braces. B). What will be the difference between braces and invisalign.

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