In case of 64 psk ther are 6 signal i i',q q', and c c'...what goes to the input of not gate in blk dia?

in case of 8 psk c there are 3 signals and c goes to input of not gate.. but what in this? if all the input goes to 3 :8 converter then what is diff b/w 64 psk and 64 qam?