It used to be something different and I don't think parity in a non-ecc ram still exists.
Probably idiotic label.
Parity: notice an error, if it's limited to one bit.
ECC: notice an 1bit error, fix it on the fly. notice a 2bit error, hopefully also log to BIOS (EFI log) and send an alert to the OS via the CPU (called MCE for machine check event or EDAC for something even dumber)
Better levels exist but only in real enterprise servers.
ECC modules cannot be used in parity mode. The reason for this is simply that the ECC module design is such that individual parity bits cannot be set, so the chipset will not write the correct data to the chips which contain the ECC word. In order for ECC modules to work properly, the chipset must be able to handle them and the BIOS must have implemented the feature properly.