Comment by dgacmu

The more correct and general answer is that:

- EDAC is a term that encompasses anything used to detect and correct errors. While this almost always involves redundancy of some sort, _how_ it is done is unspecified.

- The term ECC used stand-alone refers specifically to adding redundancy to data in the form of an error correcting code. But it is not a single algorithm - there are many ECC / FEC codes, from hamming codes used on small chunks of data such as data stored in RAM, to block codes like reed-solomon more commonly used on file storage data.

- The term ECC memory could really just mean "EDAC" memory, but in practice, error correcting codes are _the_ way you'd do this from a cost perspective, so it works out. I don't think most systems would do triple redundancy on just the RAM -- at that point you'd run an independent microcontroller with the RAM to get higher-level TMR.