I have previously compared FMEA and FRACAS, here. Another simple difference is:
(Successful) FMEA reduces risk.
(Successful) FRACAS reduces failure rates.
Now, one often hears about successful FMEAs. In my experience, these are not FMEAs, they are examples of FRACAS. An example is here. How can one tell that this is FRACAS and not FMEA. It’s simple – what is described is the reduction of a too high failure rate to a lower rate. With FMEA, the failure rate is zero – the event has not happened. What one does is to reduce the risk of this potential failure, from some amount to a lower amount. This is perhaps one of the reasons, one does not hear too much about FMEA successes. As I said before, to say that something that has never happened is now even less likely to happen (due to FMEA) just isn’t too exciting.
To reduce failure rates is a good thing and it is not a big deal to call this FMEA when it is FRACAS. However, it is simple to use the correct terms and if one doesn’t one might wind up neglecting to perform FMEA when it’s needed.