Yes, when the spirit is given a human body, it has powers that other spirits do not have. They can really grow and become a better spirit or even a bad spirit. Just depends on the choices you make in your life. Some is predestined but much of it has to do with how the spirit chooses to live. Some spirits get very attached to this world, and they are not able to fully grow. Some spirits get very distracted and fall pray to bad things and do a lot of harm to others and themselves. It's all very complicated and hard to put in words. Most of us I think do not live to our fullest potential because we become satisfied with a particular way of living and thinking. It's not a bad thing, but I think it's always good to keep an open mind to new things.
There are spirits just sent down as spirits, and sometimes they have to observe someone else who is living as a human's life. They do not have any powers, but they must learn lessons as an outsider. Some spirits are sent down to guide others too. There is such a thing as a guardian angel!
Some spirits are very spiritually high, and they come here in human form by choice. It is to guide the rest of us and help us. They give us hope and show us what we really need to be working at as human beings. I'm blessed to have met the people I have met who are like that. Some have even died, and I feel like I did not learn from them what I was supposed to learn, but perhaps the timing was not right. There will other spirits coming into my life too, so there's always room for groW*H.
Each person you are connected with is for a reason, and we have to find that reason. Sometimes I meet people and wonder why did I ever meet someone like that, then later in life I see they helped learn a lesson for the future. Life is a cycle, and we all go through to become a better soul. An analogy in a book I read talked about our spirit like a diamond. We have to keep coming back here in different forms and different scenarios to make our souls brighter and purer.
My goodness! I wrote a TON!
I actually have more to write, but I think I should stop. Don't want to bore you.