What is the difference between VIX and VXV?

Could you please elaborate on the distinction between VIX and VXV? I understand they are both indices related to market volatility, but I'm curious about the specific nuances that set them apart. How do they differ in terms of their composition, calculation methodologies, and the insights they offer to investors? Is one more predictive of future market movements than the other? I'd appreciate a clear and concise explanation of the key differences between these two volatility indices.