Sovereignty: "agency" vs. "authority"

Reading "3 Mistakes We Make When Talking about the Sovereignty of God" made me realize how often I too gloss over "agency" vs. "authority" in my thinking/speaking about God's sovereignty:

When talking about the sovereignty of God and how it relates to sin and evil, it’s important to distinguish two concepts: authority and agency. When we say that God is “sovereign,” we’re affirming that God has authority over everything that happens in the universe. 

But that’s different than saying that he directly causes everything that happens, which is a question of agency.

 [http://marccortez.com/2013/06/13/sovereignty-of-god-3-mistakes/]