Excel formulas are typed in the formula bar in the Excel window.

DAX formulas are typed in the formula bar in the Power Pivot window.

In Excel formulas, you can reference individual cells or arrays for data.

In DAX formulas, you can reference only complete tables or columns of data, i.e. references can be only to tables and fields in the tables.

However, if at all you have to perform a calculation only on a part of the column data, you can do so with the DAX functions that filter and provide the required unique data values for calculation.

Excel formulas support certain data types.

DAX provides more data types than Excel does. Hence, DAX formulas can use the additional data types also.

Excel does not support any implicit data conversions.

DAX performs implicit data type conversions during calculations.