The advantage of using the Variable is reuse. The variable defined in qlikview will be the global and they can be static or calculated.
The variable created by Variable Overview in front end that starts with the equal symbol will directly calculated by qlikview. An expression that does not start with equal symbol will not be calculated remains static.
Here the example which shows the exact difference between two usages. Let say an application has sales data per Region.
Variable called vSales that has expression to calculate the sum
vSales = (sum(sales))
When using this variable in chart will gives string sum(sales). This expression can be calculated by using $ sign before the variable.
The result will be the sum of individual regions.
When a variable is defined with equal symbol,
The result will be the total value of all regions in each row of the table.
Variable is extremely powerful in developing qlikview applications and should be used with care.
By: Sivaraj Seeman