Difference between Where and If in Webi

Two expressions

=[Revenue] Where ([Country]="US")


=Sum(If [Country]="US" Then [Revenue])

might look similar. They produce the same result if Country is not used in the table:

However with Country the result is slightly different

The expression with Where removes Country from the context, i.e. something like

=Sum(If [Country]="US" Then [Revenue]) ForAll([Country])