Copy Non-Matching Data Between 2 Sheets To Another

I am trying to find a way of comparing entries in one spreadsheet to another spreadsheet and generating a third sheet of those that do not match.

As an example, I have a spreadsheet of approved supplyers, with name, reference and date in each column, and a speadsheet of used supplyers, some with references and some without. I want to compare the supplyers used to the approved supplyers list by reference number (which are in the same format), and produce a third sheet listing all those that do NOT match e.g. unapproved supplyers.

I need to make sure that the third spreadsheet only lists each seperate supplyer once, even though they may have been used several times, AND it must also include supplyers without a reference number.

I will use this to compare many spreadsheets with the same data, but of varying length and would like to use a macro to perform this function.