A UVP focuses specifically on why someone should choose you over a named alternative. A brand message is broader and covers audience, problem, and outcome without necessarily naming a competitor.
That's valid — frame the alternative as inaction or the status quo, e.g. "unlike staying stuck," and build your difference around what changes once someone takes action with you.
Use the differentiation strength test: if a direct competitor could say the exact same sentence about themselves, your difference isn't specific enough yet.