Ok there seems to be a little misinformation going on here.
First off "THCO" is referring to THC-O-Acetate or O-Acetyl-tetr etrahydrocannabinol. It's a pretty terrible name because it's not designating where the double bond is. There are technically 6 different THCOs, d8, d9, d10, d6a10a, d6, and d7.
The vast majority of THCO is going to be delta 8 THCO, because d8 is so plentiful and cheap and acetylating it allows it to be sold anywhere in the US, even the states that have banned d8.
The 2nd most common THCO you're likely to run into is d9 THCO, but this is kinda rare. For one, most people aren't acetylating their raw d9 distillate because if they deriving it from cannabis/marijuana, then it's not covered under the farm bill and is federally illegal everywhere. While you can make d9 from cbd, it's very difficult to produce just that one double bond isomer.
I've heard that d9-THCO is more potent and psychedelic, but as someone who's made probably 1000kg of d8-THCO, I think that claim is 100% hype.
That's coming from plenty of first hand experience, plus the general knowledge that all of these acetylated cannabinoids are prodrugs to their parent compound ie d8 THCO likely hydrolyzed to d8 THC. Hence, all of these acetylated compounds are weaker by weight. D8-THCO is weaker than D8-THC. There's no logical explanation that would suggest d9 THCO doesnt follow the same trend. Some people like to say that the acetate group possibly has a better bioavailability than its hydroxylated counterpart but afaik there is no proven data to suggest that.
Lastly, while it's not proven beyond a doubt, there is logical reason to believe that smoking or vaping any of these THCO products could lead to formation of ketene, which is pretty toxic. Just because someone can put something in a vape cart, doesn't mean. It should be vaped.