The difference between RSI and QQE is that QQE is a smoothed, more advanced version of RSI with two volatility-based trailing lines built from the ATR of the smoothed RSI. The Quantitative Qualitative Estimation indicator applies a smoothed RSI and two volatility-based trailing levels (fast and slow).
QQE is an attempt to smooth the RSI in order to improve its responsiveness.
Unlike RSI's rigid 30/70 levels, QQE uses adaptive thresholds that adjust to current market volatility, meaning fewer false breakouts and more reliable overbought/oversold signals.
Traders pick QQE when they want cleaner crossover and divergence signals.