You wrote:
"2 different words used because they are different."
Words is different but they indicate the same thing. You can call your car as automobile, vehicle, or transportation, but it does no mean that you have three different cars.
You may have first name, middle name, and the last name, but it does not mean that you represent yourself in three different persons.
Bible does the same thing, it uses a figure of speech, and may naming a single thing by number of different names.
There is no difference between such words as spirit, soul, and heart, all these three words indicate SPIRIT, whatever its a Spirit of GOD or a human being.
For example:
Deuteronomy 2.30
30.But Sihon king of Heshbon was not willing for us to pass through his land, the Lord your
GOD hardened his spirit and made
his heart obstinate, in order to deliver him into your hand, as he is today.
Of course GOD cannot make a physical heart obstinate because it is a physical pump, but word "heart" under this context means spirit-soul, and repeated twice in this sentence using a different word.
Another example:
Isaiah 42.1
1."Here is
My Servant Whom I uphold, My chosen, in Whom
My Soul delights, I have put
My Spirit upon Him, He will bring forth
justice to the nations."
Does GOD have the Soul and the Spirit, of course not, it is the same thing, the Spirit of GOD, but expressed in two different words.
Isaiah 57.15-16
15.Thus says the High and Lofty One, Who inhabit eternity, Whose name is Holy, "I dwell in the high and holy place, and also with those who are contrite
(sorry, remorseful) and humble in
spirit, to revive the
spirit of the humble, and to revive the
heart of the contrite.
16.I will not continually accuse nor will I always be angry then the
spirits would grow faint before Me, even the
souls that I have made."
And here all three: Spirit, Heart, and Soul, all are mentioned together, all of which refer to the soul-spirit of men.
Deuteronomy 6.5
5.And you shall love the Lord your GOD with all
your heart, and with all
your soul, and with all your might (Deuteronomy 30.2.6.10.16.20) (Matthew 22.37-40) (Mark 12.29-31) (Luke 10.27)
How you can love with physical heart? Is you heart is not your soul-spirit?