What's the difference?
The Soul is linked to the spirit, whereas the Core is linked to the body.
The Soul is like the Core of the Spirit..
The Soul resides in the Core, which keeps the spirit linked to the body.
If the Core is removed from the body while one's spirit still occupies it, they will be sucked into their Core because that’s where their Soul is.
Meanwhile, if the Spirit and the Soul are already outside of body, they will NOT be immediately sucked into the Core. However, this will prevent them from returning to their body until their Core is reunited with it. They will also get sucked into their Core if they try to touch it while it is separated from their body.
Also, the Core requires the power of the Soul to stay alive. Without the Soul, the Core will eventually lose it's power.
Without the power of the Core, the body will then begin to die as well.