Eunomius does describe the Son as created, but he is concerned to show that the Son is distinct from the creation we inhabit: the Son is a product unlike other products and stands in the relationship of maker to all other things. The Son holds a unique status because he is a uniquely direct product of the Father’s will. Again, Eunomius carefully distinguishes activity (energeia) and will from essence. He makes use of a causal hierarchy to consider the relationships between the persons that we can schematize as essence-activity-product. In this sequence Eunomius is at pains to argue that activity is not coterminus with essence: an activity is distinct from an essence and is temporary. Only by understanding that God’s activity is an effortless willing without any consequences for his existence can we appropriately preserve the unity and simplicity of God. The Son is thus a product of the Father’s will and is the image of the Father’s will: but he is the Father’s power only in being an image of his power and activity. The Spirit is understood on the same schema, not as an activity of God that is somehow also an essence, but as a product of the divine will created through the Son and inferior to the Son.
~ Lewis Ayres Nicaea and its Legacy pg. 148