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Scope of Global Variables

Scope refers to the lifetime of the variable reference in memory. The scope depends on where the variables are declared or initialized. Whether a global variable is still accessible after a package has executed depends on how the global variable was created.
A global variable created during design time retains the value it had when the package finished execution, if the package is saved. For example, suppose you create the global variable, "city," and set it to the value of "Boston." During package execution, an ActiveX script changes the value of "Boston" to "Philadelphia." The next time you execute the package, the global variable will contain "Philadelphia," not "Boston." This is useful if you want to query the value of a package global variable after execution.
However, global variables created dynamically in an ActiveX script have two scopes. If they are created above the Function Main(), they are available to all functions in the script. This is the equivalent to module-level scope. If they are declared within a function, they are available only inside that function. This is equivalent to procedure-level scope.

Иными словами, если глобальную переменную объявить в закладке Global Variables св-в пакета, она сохраняет свое последнее значение. Если объявить динамически, т.е. где-нибудь в ActiveX Scripte написать DTSGlobalVariables("NewGlobalVariable").Value = 5, то нет.