Many a brainy theologian has set himself to discern what the scriptures say about soul vs. spirit. Every one of them who has spent years in that pursuit has come to the same conclusion: scripture doesn’t say.
While we’d love to have a clear biblical definition of “soul” vs. “spirit,” the Bible simply doesn’t give it. In fact, scripture uses the two terms almost interchangeably. Subsequently, modern christian thinkers are left with choosing a model and going with it. We often need some kind of common understanding of soul and spirit so we come up with a model just to serve common language.
Generally, “soul” is thought to be more like the seat of emotion, reactions, self-image, and “spirit” is thought of more like the seat of “executive functioning,” like our abilities that are higher than the animals (self-awareness, authority, free will, planning, organization.)
But these are loose models at best since scripture does not give us a definitive framework. Dogmatic opinions about how soul and spirit differ are just that… opinions.