Index and match & Compare Value (Been told this is not possible)

hello All

boss say’s this isn’t possible…
This is a packaging reconciliation that’s done each month..

BMW Tab
Data pasted from customer Portal.

HUF Tab
Data pasted from MRP system.

Recon Tab
I’d like this tab to report the difference between BMW & Huf Tab for each delivery note number,
The yellow tab is the delivery note number and will be on both tabs, this number changes from delivery to delivery.

I need the green columns on both tabs to compare and return the difference, making sure it reference’s the correct delivery note.

Paul

In B2

=SUMIF(BMW!$I$2:$I$1000,'Recon (Sample Results)'!$A2,BMW!$J$2:$J$1000)

in C2

=ABS(SUMIF(HUF!$J$2:$J$1000,'Recon (Sample Results)'!$A2,HUF!$B$2:$B$1000))

in D2

=IF(B2=C2,"OK",B2-C2)