"Second one is simplest, because we honestly don't really know - the records are patchy at best, and the Power stone is... Inert, in a way the others aren't. All of the other five have been known to act on their own sometimes - Time, Space, and Reality generally fairly basically, but Soul exhibits at least an animal level of intelligence, and the Mind stone is generally suspected to be sapient. The Power stone though just - sits there, unless someone tries to use it, at which point they inevitably cause a massive and undirected explosion and the stone usually then vanishes from the records for a few centuries. The Power stone is also considered the hardest to identify for that reason."
"Thanos thinks it's required to use the other stones to their full potential. I'm... Doubtful that that's all it does."
"Time and Space are different from Reality because Reality covers the more fundamental - way the world works. Magic especially. Space lets you move things around at the most basic, and be in multiple locations at once if you have better control of it - it's one of the better understood stones since it's more active than most. Time is... Difficult to find, since it moves itself around in the timeline, and not much is known about it beyond that it enables time travel."
"Mind and Soul are - fundamentally different things, and they're also basic properties a thing can have. You don't need to have one to have the other - we're not entirely sure how things acquire souls, I think figuring that out would require some very unethical" but fascinating "experiments with the Soul stone, but we know roughly how minds emerge. Minds are... Very simply, anything mind magic works on, anything that reacts with intelligence to its environment and has memory. Simple computers are the most common things with minds but not souls - computers can definitely have souls, but I don't know why some do and some don't. And people who are brain dead usually have a soul, but don't have a mind."
" - Those six are also fairly fundamental divisions in magic, though there's usually some obfuscation built on top of it."