"The ontological Trinity concerns God as He is in Himself, unrelated to the world, while the economic Trinity concerns God as He stands in relation to creatures. Ontologically, the three persons, being underived and perfectly equal, do not stand in any relations of subordination. But in relation to creatures, for the sake of our salvation the second person of the Trinity submits to the first, taking on a human nature, and the third person acts in the place of the second, continuing the ministry of the Son between his ascension and return. So in the economic Trinity there are relations of subordination among the persons of the Trinity.
What's important to understand is that subordination does not imply inferiority. The Son and the Father are in every respect co-equal, but out of love for us and for the sake of our salvation, the Son submits to the Father. The Trinity thus provides a beautiful model of the family, in which the wife, though co-equal with her husband, willingly submits to him. Feminists who denounce such submission on grounds of inequality have failed to understand that functional submission need not spring from inferiority but can be undertaken among equals for the sake of some overriding aim."