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Answer: The "Completed Orders" report provides the details only for orders that occurred on that day, whereas the "Sub-Id" report shows the ountcome outcome of the clicks that occurred on that day. The reason for the difference betwen between the two reports is that customers often click a link initiating a checkout, but then don't end up puchasing purchasing that day, but they end up coming back and completing their purchase a short period after the initial click through (usually 1-2 days later). The Sub-Id" report reflect that behavior.
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