When are they used:
AVERAGE :- You use the AVERAGE function in Excel to return the average (arithmetic mean) of the specified cells.
Example 1. Calculating an average of numbers To find out an average of certain numbers, you can supply them directly in your Excel average formula.
=AVERAGE(1,3,4) returns 2.67 as the result.
AVERAGEIF :- The classical use of the AVERAGEIF function in Excel is finding an average of cells that exactly match a given criterion.
Instead of entering the condition directly in a formula, you can type it in a separate cell and refer to that cell in your formula:
AVERAGEIFS :- The AVERAGEIFS function in Excel is a plural counterpart of AVERAGEIF. It allows for multiple conditions and returns the average (arithmetic mean) of cells that meet all of the specified criteria.
AVERAGEIFS(average_range, criteria_range1, criteria1, [criteria_range2, criteria2], …)