There is a difference between risk factors and risk premia. This may be viewed as a subtle distinction, but it is important to think about the differences. Factors explain the return attributes of an asset. Those attributes may be either style or macroeconomic factors. Factors provide a description of what drives returns. A risk premium is what an investor receives for taking-on the risk associated with a factor. A risk premium is compensation for non-diversified risk which can come in the form of a style or a macro factor. A factor is a measurement of a characteristic. A premium is compensation for holding a characteristic. Investors want to be paid a premium for a persistent repeatable factor.