The main property of the 1st level, "matter," is pure actuality, and especially simplicity and freedom.
The main property of the 2nd level, "spirit" is perfect and unlimited happiness.
But that includes virtually pure actuality. For if God the Son is perfect, then included in the meaning of perfection is complete safety from losing any perfections or the happiness stemming from them. The Son is pure act, because there is no potency in Him toward either greater or lesser happiness, knowledge, or anything else predicated of Him.
But not vice versa: perfection is a value judgment; pure actuality is entirely descriptive. So, a thing may have no potential for change yet still be imperfect.
The main property of the 3rd level, "goodness," is unconstrained creative power.
That again includes virtually both complete happiness and pure actuality. Suppose that God was not completely happy and created because, for example, He wanted company. Then it would no longer be true that God "wills nothing except by reason of its goodness." (ST, I, 19, 2, reply 3) He would have created because of the utility to Him of the creation which would be good as a means to the satisfaction of God's "selfish" ends. In other words, there would be an evil in God which the creation would help remedy; and therefore, the creation would spring from something evil rather than from something good.
But again, not vice versa: thus, God the Son is maximally happy in Himself but has no creative powers and so is not good like the Father.