Your Unique Value Proposition (UVP) is a conversation you have with your customers on why they should hire your product and fire their existing alternatives (including current competition).
Your Unfair Advantage (UA) is a conversation you have with your competitors (current and new) on why they should NOT try to hire away your customers.
Sounds similar but it’s a subtle yet critical difference in perspective.
Facebook’s UVP to users is come use us because we have all your friends on the network already.
Their UA to competitors is don’t bother stealing our users because we have already everyone and their friends on the network.