RTP is a game’s long-run return; the house edge is the casino’s average share:...
https://www.apu-bookmarks.win/rtp-is-a-long-run-average-not-a-promise-for-one-session-at-96-rtp-the-house
RTP is a game’s long-run return; the house edge is the casino’s average share: 96% RTP means a 4% edge. Volatility affects how often and sharply results swing. Short-run results can differ widely from the average, so don’t expect a session to match it.