Excel Data Integrity Task between Databases

first off you say "completely different naming conventions" so is the supplier Name the same in each or not? if not that is much more difficult. If so then yes a conditional formatting similar to what you suggest can work. If you have excel 365 then maybe use XLOOKUP as that has the if_not_found built in and more efficient. Either way I suggest using additional columns on the database B to show the values from database A. So IMHO I would probably to the right of database B do something like =XLOOKUP(databaseB[supplier], databaseA[supplier], databaseA[ccc], "na") where ccc would be the column to return and you either copy that formula for each column or use REDUCE and LAMBDA to create it all at once. If you send/attach/give link to a sample workbook without personal / private info I would be happy to give an example