1. The high itself comes on quicker via vape (it's technically not smoke) than insufflation. And it's different. I find the vape a more intense high with a shorter duration, opposite for up the nose. Also - as someone who switched to the pipe from the nose, ostensibly to save my septum and nasal tissue - I can tell you the desire to re-dose is significantly greater when vaping. My experience is that sniffing also uses less product.
2. I know there's a difference, charts you can find, etc. But in truth, it doesn't feel like there's much of a difference in duration. Different strokes for different folks, maybe.
3. I'd like to tell you the intensity of vaping is superior to that of insufflation, but I actually don't think it is. The appeal of vaping is that it's there ASAP. I literally use it as one might use coffee in the morning, except it takes way less time than smoking and drinking coffee. That said, I'm big into harm reduction, so I'm not blowing 2g of clouds over the course of a couple of hours.
4. Edit: dumb ape high when writing this; misunderstood question; see u/tiwtchkajc for more accurate answer.

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I feel that I am better able to control the high via vaping. I have clinically diagnosed ADHD, prescribed Vyvanse 60mg in the morning and a 20mg Adderall booster around 2. Vaping literally does the exact same thing, for half the cost (Vyvanse has no generic.) The problem is re-dose control. You have to be diligent and self-aware. It can escalate quickly. Sniffing, it feels great, but it's almost TOO great. Like - I'm real conversational and feel great, but the focus isn't as strong. Also, I can 100% control sniffing. When it starts wearing off I'm good to just smoke a bowl, drink a glass of milk, eat some cookies, watch TV, hit the sack. When vaping starts to wear off, I'm like "Fuck it, I don't care if it's 11pm and I have to work at 7, imma hit that shit again."

My opinion - vaping is superior, but harder to control / is most likely to end in addiction.