What is the Difference Between the Holiness of God and His Righteousness?

In the first volume of Geerhardus Vos’s Reformed Dogmatics, he answers the question of the difference between God’s holiness and righteousness:

What is the difference between the holiness of God and His righteousness?

Those two attributes are most closely connected to one another, yet they are not to be identified with each other. The difference is mainly twofold.

a) We call holiness the rational goodness of God as He possesses that in Himself, without our understanding that goodness as moving outside of Himself. On the other hand, righteousness is specifically that attribute of God's being that compels Him to make His holiness a power outside of Himself.

b) Holiness is, as we have seen, God's determination toward Himself. It is, as it were, a centripetal property, by which God moves toward Himself, toward the center of His being. On the other hand, righteousness is more a centrifugal property, by which God works from Himself outwardly, although this also occurs to reveal and maintain His holiness.

God moves in two directions: toward himself in holiness and toward his people in righteousness. If God were to move only toward himself, he would still be God. But by moving also toward his people in his holiness, he brings more glory to himself than he otherwise would. The holiness of God separates us from him. The righteousness of God unites us to him.