None.
It's more durable. It's rock solid reliable. It has a longer warranty and which can be doubled for a fee. It's short protection is second to none. You can get a good resistance reading without a separate meter which can be handy. It's output is very well regulated that remains completely independent of battery charge. Replacement/spare
batteries are usually less expensive than another spinner.
It's not a magic item that will make your vape suddenly turn into a wondrous thing. It won't make bad
juice good. It won't make you look cool.
I'm really hard on my PV. I've gone through well over a dozen
batteries plus 3 mods before I obtained my ProVari. It's worn and shows some scars, but it's still a reliable unit and I almost always have it with me. It was a good value for someone like me. It's not for my sister who can keep a Twist going along just fine for a year, maybe more. There is nothing wrong with her vape or anything my ProVari could improve for her.