RTP is a game’s long-run average return; the house edge is the share it keeps....

https://www.quantifiedstrategies.com/rtp-variance-and-expected-value-applying-a-quantitative-framework-to-online-casino-gaming/

RTP is a game’s long-run average return; the house edge is the share it keeps. At 96% RTP, the house edge is 4%. Volatility shapes the swings, but short sessions can land far from the average in either direction.