RTP is a long-run average; house edge is the casino’s expected share of wagers:...

https://lunasuniqueinsight.inkharbory.com/posts/is-there-any-strategy-that-changes-the-expected-value-on-slots

RTP is a long-run average; house edge is the casino’s expected share of wagers: 96% RTP means a 4% house edge. Volatility measures how uneven results can be. Over a short session, wins or losses may differ sharply from the average.