When you execute a script, it affects the workspace of any currently executing function; if no function is currently executing then the script affects the "base" workspace.
Variables do not "belong" to scripts; variables live in the workspaces.
You cannot ask that only a certain variable in a script be calculated: you can only ask that the entire script be calculated, after which any variables it created or changed would be in the appropriate workspace. So if script A needs a variable from script B, then A can execute B and then the variable will be in the current workspace.
Scripts are different than functions. There is no way to get at a variable that lives inside another function's workspace -- not without the cooperation of the function.