RTP describes the share a game is designed to return over time; the house edge...

https://varimail.com/articles/does-session-timing-matter-in-online-casinos/

RTP describes the share a game is designed to return over time; the house edge is the casino’s expected share. A 96% RTP means a 4% house edge. In a short session, results can swing sharply—past outcomes don’t guarantee what happens next.