The standard deviation is a measure of dispersion. It is the average difference (or gap) of observation from the mean of the data. Its unit of measurement is the unit of the original data (e.g., cm, kg, m, or km).
On the other hand, the coefficient of variation is the ratio between the standard deviation and its mean. It’s unit-less (do not carry the unit of the original data). Hence, the variation or dispersion of one data set can be compared with other data set with the same or different unit of measurement. Example, the variation of weights of seeds can we compared with variation of distance of trees in an area.
Hope this helps.
The 365 Team