HMDA Geocode-FFIEC vs US Census

We have always validated our geocode by using the FFIEC site and our LAR reporting software also uses the FFIEC as its standard. However, we have a LOS vendor now who does not use the FFIEC and instead uses the US Census Bureau. There are several differences that I have found between what the FFIEC states is the correct census tract and the US Census Bureau. It is my understanding that most institutions use the FFIEC because that is the "unofficial preferred" method of examiners. Can anyone tell me if you are using the US Census Bureau to geocode, and why? Or FFIEC and why?

FFIEC because that's what my FED examiners use. end.of.story.

Ditto Truffle's reply.