No they are not all the same, not in a million years.
IMO the attachments that fit onto an ordinary light stand are just plain dangerous, very few stands have anywhere near the necessary rigidity or size of footprint. They're not designed to take the extra stress of supporting a flash head and modifier, plus a counterbalance weight - it's much better to spend a bit extra and get a boom arm with its own stand, made specifically for the job. And get one that can take the weight of a heavy flash head and the heaviest possible modifier, for safety.
And even when you do that, you need to balance the boom arm so that the locking lever is only used very lightly, to prevent any small movement - you need to balance both the amount of extension and the counterbalance weight so that it won't move even if you don't tighten the locking mechanism in the centre. And even then, you need to make sure that one of the stand legs is pointing towards the flash head, so that the whole thing can't fall over