Compare data and summarize on seperate sheet

Hello,

Each month I download a 1,000+ line of Part Numbers with inventory qty and value to an excel tab. I want to compare the part numbers to see which one inventory is increasing or decreasing.

The row header would look like:
Part Number - QTY on Hand - Value
123 1,000 $10,000

I would like to have a summary tab so each month we can see each part number and if its inventory is increasing or decreasing. Can I get the formula to do this?