Redundant tag. Implicates a specific raceplay marking or tattoo that falls under queen_of_spades_symbol. This tag appears in certain imageboards which bore no use on Danbooru for general users except for those who are into latter mentioned tag.
They're different things. Just because they're used for the same fetish doesn't mean they should be aliased.
Obviously the tag is used by people who are into the tag, that's not a reason to alias it either.
They are the same thing. Spade_vine_tattoo is the same as the queen_of_spades_symbol tag since it's part of the same spade-shaped raceplay markings for QOS-tagged posts. They can only be different things if it was a regular vine tattoo without using a specific shape as the leaves. queen_of_spades_symbol involves spade-themed imagery. No one uses vine tattoos with spade-shaped leaves or would even tagged it unless it happens to be QOS.
https://danbooru.donmai.us/posts/8168918 is the first post added with spade_vine_tattoo even though already has the queen_of_spades_symbol tags beforehand. This is an oddly specific but pointless tag. We don't need new useless tags for specific QOS markings. spade_vine_tattoo could alias to spade_tattoo but it's not spade_(shape) tattoo and is still a queen_of_spades_symbol