No there is no difference it is simple a passive adapter. I think you can buy such an adapter 2 or 3 bucks and production cost is probably a couple cents.
The rest is just a mounting bracket.
The space in there is so tight that just about anything would work. There is no need for 5 screws or what ever to sit perfectly in place. With a bit of improvising you won't need any screw at all. Just a bit of stuff to fill any gap so it is crammed in there tight enough so it cannot move.
If you pay up you do it only for those screw holes as some ebay optibays aren't perfect in that regard but it really is a waste of money, unless you run around without the bottom cover all the time

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I would just get one of the cheapest ones you can find on ebay from a seller with good ratings.
That stuff costs regardless of design pretty much nothing to produce. If you pay to much you simply do pay to much.