What does QPSK and 8PSK mean?
QPSK or 4PSK is 2 bits (4 states) per symbol or waveform
8PSK is 3 bits (8 states) per symbol
8PSK is 50% more data per symbol then QPSK, but it requires more power since the receiver has to figure out which of 8 possible states the waveform is in verses 4. So, more error correction is used, so not 50% more but about 30% more data in practice.