What is the difference between an EVP and a slogan?

A slogan is a line; an EVP is the substance beneath it. The EVP is the actual promise, meaning what you ask and what you give, together with the proof that makes it believable. A slogan may distil that into something memorable, but it is a summary, not the strategy. The distinction matters because organisations frequently invent a catchy phrase and mistake it for having done the work, leaving nothing real underneath. If you deleted the slogan tomorrow, the EVP would still exist as a set of commitments and evidence. The pitfall is starting with the tagline: get the truthful promise and proof right first, and only then decide whether it even needs a slogan.