Compute Variance Qty

[sgwong]

Compute Variance Qty from source data and outo

[CoG]

Looking at your attachment, I am a little confused by the ask and wanted to verify the details. It appeared to be a simple case, where you separate the two datasets, Summarize them, then Join them back together, and use the Formula Tool to compute the difference between the two columns. 

That being said, the output sample you provided ignores the Date2 field completely and aggregates both Qty fields by grouping Date1 only. If this is the case only 1 Summarize tool is needed, and then the Formula Tool, and that's it.

Please provide clarification on your specific use case to receive better assistance. Thanks!