John 1:1 is used many times to infer that Jesus is God. If that is so, why are the 2 Greek words for "god" in that verse different?

The first Greek word for God is θεόν. The second Greek word for God is θεὸς. They are clearly different words. Some Bible translations use all capitals for the first instance and all small letters for the second to make the distinction between God and Jesus. 2 Corinthians 4:4 uses the same Greek word as in the...