In statistics, sx refers to the sample standard deviation. It is a measure of the amount of variation or dispersion of a set of data values from their mean. The formula for calculating the sample standard deviation involves taking the square root of the sum of the squared differences between each data point and the sample mean, divided by the sample size minus one.

On the other hand, σx (sigma-x) refers to the population standard deviation. It is a measure of the amount of variation or dispersion of a set of data values from their population mean. The formula for calculating the population standard deviation involves taking the square root of the sum of the squared differences between each data point and the population mean, divided by the population size.

In summary, sx and σx are both measures of variation or dispersion, but sx is used for samples and σx is used for populations.