RTP describes the long-run average return; the house edge is the casino’s...
https://www.quantifiedstrategies.com/rtp-variance-and-expected-value-applying-a-quantitative-framework-to-online-casino-gaming/
RTP describes the long-run average return; the house edge is the casino’s expected share. A 96% RTP means a 4% house edge. Volatility affects how wins and losses are spaced—short sessions can swing sharply, so results may differ a lot from the average.