The last full season I watched of The Voice only had 2 live rounds, including the finale. This past season of AI had 8, and the final 2 performed a total of 21 times throughout their runs. AI is a much more demanding show.
As for the level of talent, I think once you get to the top 8-10, it’s pretty close, and as I mentioned above, AI contestants are challenged far more.
I also don’t think AI uses much autotune for the pre-lives, while we all know The Voice does. They are basically studio recordings by the time the editors are done with them.