Show Difference of sheet1-sheet2 in sheet3 if items match?

Basically I have two lists in sheet 1 and sheet 2. Column a is the item number and col b is the quantity. In sheet 3 I basically want it to show all items in col a and in col b the difference of sheet 1 - sheet 2. If the same items don't exist it will just now show up. Is this something to do with vlookup?

EDIT: Attached sample file.

Hello ! try this in sheet 3 in B3
=IFERROR(VLOOKUP(A3,Sheet1!$A$2:$B$6,2,0),0)-IFERROR(VLOOKUP(A3,Sheet2!$A$2:$B$5,2,0),0)

this formula will count 0 for the item if item does not exist in any of the sheet i.e. 1003 is not available in sheet 2 but is available in sheet 1 then result will be 11-0=11, if we reverse it then 0-11= -11