Find Replace compares a field in the F input with a reference field in the R input. It can replace matching text or append selected lookup fields. Choose the match scope deliberately: an entire-field match protects a code from an accidental partial replacement. Case sensitivity is separate from that scope, so lowercase source codes may need an explicit ignore-case setting.
Append Fields attaches every source record to every target record. A one-row reporting parameter repeats once on each target record. Two parameter rows create two output records for every target, which can double a later total. This is a Cartesian product, not a keyed lookup. Keep the parameter source small and inspect the output count before using it in a business report. Both tools need clear input roles as well as correct field names.