Both scalar and aggregate functions are used to manipulate fields of data. The main difference between the two functions is that the scalar function is used to manipulate the portrayal of a data field. Whereas on the contrary, the aggregate function performs a set of calculations of a particular column of data and returns those results in a new summarized field. For example, if we were to use the aggregate function AVG() on a column of data that says 3, 2, and 1. After executing that query, a calculated field will appear with the result of 2 because that is the average of the three data values. Conversely, if we use a scalar function such as ROUND() to a particular data field that says 3.1415926, and depending on accurate you want to be with your rounding, and if up to a whole number, it would just simply say 3, or to whatever places of decimal points designated within that ROUND() function.