If you measure from the bottom of the U between teeth to the bottom, directly opposite and both are the same distance apart, then they should have the same ratio regardless of teeth. It's the size around that determines the ratio. The reason why one has more teeth than the other, but they are the same size around it that the 630 chain's sideplates are longer than the 530's therefore the 630 sprokets will have less teeth for the same ratio.
I could be wrong. anyone please feel free to correct me on this.