From: https://plato.stanford.edu/entries/value-theory/
“But in a more useful sense, “value theory” designates the area of moral philosophy that is concerned with theoretical questions about value and goodness of all varieties — the theory of value. The theory of value, so construed, encompasses axiology, but also includes many other questions about the nature of value and its relation to other moral categories. The division of moral theory into the theory of value, as contrasting with other areas of investigation, cross-cuts the traditional classification of moral theory into normative and metaethical inquiry, but is a worthy distinction in its own right; theoretical questions about value constitute a core domain of interest in moral theory, often cross the boundaries between the normative and the metaethical, and have a distinguished history of investigation. ”