1 Thessalonians 5:23 "And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ."
Hebrews 4:12 "For the word of God is quick, and powerful, and sharper than any twoedged sword,
piercing even to the dividing asunder of soul and spirit, and of the joints and
marrow, and is a discerner of the thoughts and intents of the heart."
These verses tell us they are different things. Some word studies of the words have lead people to conclude that animals have souls but not spirits. I haven't gone too deep into that yet. If that is true though, it would probably mean that Biblically speaking every use of the word "Soul" in the Buffyverse should be Spirit.
The doctrines of Soul Sleep and Annihilation often go together. I've seen people argue "Soul" just means a living thing and the idea of an immortal Soul with Conciseness when separated from the Body isn't Biblical.
Often this view is built using verses from Ecclesiastes, that book is not for building doctrine, it is mostly describing how things appear to be to Man's perspective in order to refute all that at the end.
Now I believe the Belief in a literal Bodily Resurrection is vital. Some have suggested that "what is the point of the Resurrection if the Soul and Spirit are immortal and aware?" My answer is, because you lack something vital when separated from the Body.
Demons are spirits that lack a body, and they are desperately trying to steal one. I used to believe they were the disembodied spirits of Angel-Human hybrids who died in the Flood. But I no longer believe in Angel-Human hybrids.[[I've changed my mind on that even more since.]]
People often argue we see Angels have physical Bodies in a sense so Demons can't be fallen Angels. But Jude 1:6 tells us the Genesis 6 angels gave up their Oketerion. I believe that means they lost their Angelic bodies and become evil spirits/demons. The only reason for assuming the ones imprisoned in the Abyss were imprisoned there before The Flood is the apocryphal First Enoch. I now believe they were chained there by Jesus in Nisan of 30 AD, Paul tells us the Abyss was one of the places Jesus went, Romans 10:7 and Ephesians 4:7-10. And more demons get added when we do proper Spiritual Warfare.
While I agree the account of Lazarus and the Rich Man in Luke 16 is a parable we shouldn't build doctrine on. Ezekiel 32 clearly describes those dwelling in Sheol as having conciseness. 1 Peter 3:19-20 and 4:6 says Jesus preached the Gospel to the Spirits in Hades when he descended there between his Death and Resurrection (also implied in Philippians 2:9-11). And Revelation 6 tells us when the 5th Seal is opened that the Souls of the Martyrs are under the Altar in Heaven and very aware. Revelation 7 further describes these Souls in Heaven pre-Resurrection, the Resurrection/Rapture doesn't happen till the 7th Trumpet is sounded.
Jesus promised us that we will NEVER die, John 11:26.
So the Doctrine of Soul Sleep isn't supportable.
Anihaliationism is refuted by that we see The Beast and False Prophet clearly described as still being in the Lake of Fire over 1000 years later.