I watched this video a while back on YouTube Comparison: Selenite VS Satin Spar and she does a wonderful job explaining the two. Are they the same thing? She claims in the video by saying “…yes and no. Both are selenite which is a form of gypsum… Just in different forms…”. They both make up the same chemical composition CaSO4 · 2H2O (Hydrous calcium sulfate).
https://www.crystalguidance.com/selenite-vs-satin-spar/
Both Selenite & Satin Spar will have pretty much the exact same metaphysical properties. So I would not get upset about which form you have. Both forms are authentic and one is not considered a “fake version” over the other.
Hope this helps explain a bit better! 
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