Why is the coefficient of variation often a better risk measure when comparing different projects than the standard deviation?

While we want to compare the risk of investments which have different means, we make use of the coefficient of variation (CV).  The CV denotes the standard deviation's percentage of the mean.  As the CV is a ratio, it adjusts for differences in means, whereas the standard deviation does not.  Hence the CV provides a standardized measure of the degree of risk that can be employed to compare alternatives.