According to Strong's Concordance there are a potential some overlap, that may justify that a "soul" or "spirit" means "a living being or person" if you imply that "breath" means the person is alive:

According to these definitions, some may argue that both soul and spirit refers to a "living being" that "breaths" because all living creatures breaths somehow. However, there is much more to it than simply referring to a "living being".

O God, the God of the spirits of all flesh, shall one man sin, and will you be angry with all the congregation? -- Numbers 16:22 (ESV)

“Let the Lord, the God of the spirits of all flesh, appoint a man over the congregation... - Numbers 27:16 (ESV)

This implies that God each man has his own spirit.

It seems like the human spirit could also become very powerful. For example:

Elisha said, “Please let there be a double portion of your spirit on me...” -- 2 Kings 2:9 (ESV)

Now when the sons of the prophets who were at Jericho saw him opposite them, they said, “The spirit of Elijah rests on Elisha.”
And they came to meet him and bowed to the ground before him.
And they said to him, “Behold now, there are with your servants fifty strong men. Please let them go and seek your master. It may be that the Spirit of the LORD has caught him up and cast him upon some mountain or into some valley.” -- 2 King 2:15 (ESV)

Note that the same "sons of the prophets" differentiate between the spirit of Elijah and the Spirit of the LORD. Elisha did not correct them on the way they attributed "the Spirit of the LORD" to Elijah.

Possible explanations:

• This may imply that human spirits might also be able to do miracles to some degree.
• The "spirit of Elijah" is the Holy Spirit. Perhaps Elisha did not bother to correct the men or to acknowledge the Holy Spirit.

Spirit

The spirit of man is the lamp of the LORD, searching all this innermost parts. -- Proverbs 20:27 (ESV)

• Only the spirit knows the person's thoughts (1 Corinthians 2:11)
• Search for God or the other way around (Psalm 77:6, Isaiah 26:9, Proverbs 20:27)
• Help the human to understand wise things (Job 32:7-10)
• Constrains the human (Job 32:17-18)
• Can be committed
  • to God, by repentance (Psalm 31:5, 32:1-2, 34:18; Isaiah 66:2; Matthew 5:3; Ephesians 4:22-23)
  • against God (Job 15:12-13, Psalm 78:5-8)
• Can provide skill (Exodus 28:3)
• Can nourish/sustain the body in sickness (Proverbs 18:14)
• Can rule your spirit/emotions (Proverbs 16:32, Proverbs 25:28)
• Can be willing / stirred up (Psalm 106:32-33; Mark 14:38; 1 Chronicles 5:26; Ezr 1:5; Psalm 51:12; Haggai 1:14-15)
• Can be unwilling / hardened (Deuteronomy 2:30)
• Can be patient or hasty (Proverbs 14:29, Ecclesiastes 7:8-9)
• Can be humble or proud (Proverbs 16:18-19, 29:23, Galatians 6:1)
• Can deceive (1 Kings 22:21-23)
• Can sleep/slumber (Isaiah 29:10, Romans 11:7-8)

Soul

• Has desires (Proverbs 13:19)
  • Can desire God (Isaiah 26:9; Psalm 42:1, 63:1,8)
• Magnifies the Lord Jesus (Luke 1:46)
• Can be obedient or disobedient
  • Must obey governing authorities (Romans 13:1; Hebrews 13:17)
  • Must obey God's commands (Deuteronomy 30:2,10; Leviticus 26:15)
  • Purify your soul by obeying the truth (1 Pet 1:22)
  • Soul can sin (Micah 6:7; Habakkuk 2:10)
  • Soul can lust (Genesis 34:3,8)
• Greatest sacrifice is to love God with all the heart, understanding, soul and strength (Deuteronomy 6:5, 10:12, 11:13, 13:3, 30:6; Josh 22:5; Matthew 22:37; Mark 12:33)
• Cannot be killed by man (Matthew 10:28)
• You can
  • speak to your soul (Luke 12:19)
  • forfeit your soul (Matthew 16:26; Luke 12:20)
  • bind your soul by an oath? (Numbers 30:2 KJV)
• God can abandon a soul (Psalm 16:10)
• Can experience violence? (Proverbs 13:2 KJV)
• Can bless persons (Genesis 27:4,19; Psalm 103:1)
• Can rest (Matthew 11:29)
• Can shout and sing (Psalm 71:23)

Similarities

Viewpoints

According to endofthematter the two main viewpoints are:

Trichotomy

They believe:

• Humans have a body, soul and spirit.
• Each is a distinct entity.
• The soul is the mind, will and emotions, i.e. what we think and feel.
• The spirit is gives us the ability to have an intimate relationship with God and is made alive when believers are reborn.

Proof:

“For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and of spirit, of joints and of marrow, and discerning the thoughts and intentions of the heart.” -- Hebrews 4:12

However, the author of Hebrews did not necessary meant "division of soul from the spirit". The original Greek it states:

The Greek words "τε" and "καὶ" has multiple meanings which are translated to the English word "and" that could change the meaning of the verse. For example the same verse could also be translated or understood as:

For the word of God is living also active also sharper than any two-edged sword even piercing to the division of

• soul namely spirit,
• and (both) of joints namely marrow,
• also discerning the thoughts namely intentions of the heart.

So there are at least 3 possible ways to interpret this verse:

"The word of God is... dividing things in the spiritual, physical and imaginary dimensions"

In each case the author choose 2 things that are supposedly tightly integrated with each other and hard to separate.

• Because there are so little information about souls and spirits in the Bible, one cannot make an argument for or against the division of the soul and spirit based on these few words.
• Joints and marrow are odd choices. Both joints and marrow (bones) are relatively easy to separate as it sometimes happen by accident in sport injuries without the intervention of God's word. Unless the author meant to separate marrow from bone (not joints) as wild animals would spend a long time to chew on the bones of their preys to separate the marrow.
• thoughts are the development of an intention or plan and intentions are the expected product of an action; Perhaps the author meant that the word can identify a thought and reject a thought that goes against an intention.

The same verse could also be interpreted as:

"The word of God is... dividing the soul (also known as the spirit) from the joints (also known as the marrow) which is the discerning of the thoughts and intentions of the heart"

Separating spiritual (life) and flesh (death) seems to be a common theme the author keeps going back to. It could mean that the author meant that the word of God must judge every thought and intention because the result of those thoughts and intentions could either lead to life or death.

"The word of God is... dividing the soul (but more specifically the spirit) as well as it could also divide the joints (but more specifically the marrow) as well as thoughts (but more specifically the intentions)"

This implies that the word of God is powerful enough to divide or judge immaterial as well as material things.

The next verse is:

And no creature is hidden from his sight, but all are naked and exposed to the eyes of him to whom we must give account. -- Hebrews 4:13

The author likely referred to:

And Simeon blessed them and said to Mary his (Jesus) mother, “Behold, this child is appointed for the fall and rising of many in Israel, and for a sign that is opposed (and a sword will pierce through your own soul also), so that thoughts from many hearts may be revealed.” -- Luke 2:34 (ESV)

However, Simon did not mention the "spirit" and he also did not mention anything about "marrow" and "joints" which may support the last interpretation.

Regardless how you interpret verse 12, the author is making the point that all creature, whether spiritual or flesh or hidden thoughts are subject to the judgement of the word of God.

I think it is safe to say that the author did not write down this verse with the intention to give a Scientific lesson to name the composition of the human being. So this verse can unfortunately not be used in isolation to proof that the soul or spirit is the same thing, a subset of each other or separate things.

The next proof that support Trichotomy:

“Now may the God of peace himself sanctify you completely, and may your whole spirit and soul and body be kept blameless at the coming of our Lord Jesus Christ.” -- 1 Thessalonians 5:23

A possible explanation could be that Paul list every possible term known to the Greek in Thessalonians to make the point that your whole being should be kept blameless. Just like Jesus did when he said:

“And you shall love the LORD your God with all your heart and with all your soul and with all your mind and with all your strength.” -- Mark 12:30 (ESV)

Jesus did not mean that human beings were composed of 4 components. He meant that you should love God with your whole being.

Some who believe in the trinity doctrine and who believe that we are made in the image of the Godhead may logically conclude that God is made up from:

However, there are no biblical scripture to support this theory. Jesus was not God's avatar on Earth as Jesus was alive with his own soul (Matthew 26:38; Mark 14:34; John 12:27; Acts 2:27,31) or spirit (Mark 8:12; John 11:33, 13:21) too.

Dichotomy

They believe: The spirit and soul is synonymous to each other.

Proof:

There are many scriptures that refer to the entire human being, but in each case the human being is only composed of two components but described differently:

The "soul" and "spirit" shares a lot of similar attributes.

If the "soul" and "spirit" are distinct, then this verse fails to mention the "spirit":

“And do not fear those who kill the body but cannot kill the soul. Rather fear him who can destroy both soul and body in hell.” -- Matthew 10:28

If the "soul" and "spirit" are distinct, then these verses fails to mention the "soul":

And the unmarried or betrothed woman is anxious about the things of the Lord, how to be holy in body and spirit. -- 1 Corinthians 7:34 (ESV)

For as the body apart from the spirit is dead, so also faith apart from works is dead. -- James 2:26 (ESV)