Ahh... you should have mentioned that you are referring to materials science. We thought you were talking about mathematical planes...
Anyway, those are vectors, they're just used to identify crystalline planes. It's been a few years since I've had materials science, but I would say you probably still don't have enough information. They might be the same plane, they might be parallel, but why does it matter? What are you trying to solve? If you're trying to determine how a particular material will fail, then I would say that it doesn't matter. The vector refers to a direction, or a family of planes, not one specific plane.
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