what I meant is that smallest unit that RS can correct is one word, which usually is byte. So 8 bit errors in one word can be restored with less EC than 8 bit e

what I meant is that smallest unit that RS can correct is one word, which usually is byte. So 8 bit errors in one word can be restored with less EC than 8 bit errors in different words. In case of BCH, location of bit errors does not influence error correction strength, so it is more suited to correcting independant bit errors, while RS is more suited for bursty/whole block errors.