Understanding the Latin emphasis on the divine simplicity how would this distinction between Greek terms play a role in the Western tradition expressing the consubstantial communion between Father and Son first?
The East understands the simplicity of God differently than the West, because the East did not accept the pagan Greek notion of simplicity that ultimately influenced Scholastic theology in the high middle ages.
In Byzantine theology the divine essence is utterly simple and indivisible, and because of its simplicity and indivisibility it is incommunicable; while the same Tri-hypostatic God who is simple in His essence is truly manifold in His energies, and because He is manifold in His energies it becomes possible for us to participate in divinity. The heretic Barlaam also was confused about the doctrine of divine simplicity and attacked St. Gregory on that issue, and in response to Barlaam's attack St. Gregory said the following: "Hence, when we know His energy but not His essence, we do not commit an outrage to the supernatural character of His simplicity. And when we participate in His energy but not in His essence, do we make the undivided divisible? You heard him [St. Basil] also say: 'The energies of God are manifold, but His essence is simple.' Just as He who is manifold according to His energies is not manifold and divided according to His essence, so in the same way, He will not be participable according to His essence although He is participated according to His energies" [St. Gregory Palamas, "Dialogue Between an Orthodox and a Barlaamite," no. 44]. For St. Gregory, and the Eastern Churches in general, the distinction between essence and energy in God must be real, and not merely noetic, because to deny the reality of this distinction – without a separation – would be to deny the reality of theosis
. There can be no participation in the divine essence because the divine essence is simple and participation in it implies division, which is not possible; while, on the other hand, God's energies, which come down to us as a gift of grace from the Father, Son, and Holy Spirit, are manifold and consequently participable, and this very communicability is what allows for our real divinization.