RTP estimates how much a game returns over time; the house edge is the casino’s...

https://wiki-tonic.win/index.php/What_Does_%E2%80%9CTheoretical_Return%E2%80%9D_Mean_on_a_Slot_Info_Page%3F

RTP estimates how much a game returns over time; the house edge is the casino’s average share. A 96% RTP means a 4% house edge. Volatility shapes swings: results can vary sharply, and a short session may not match the long-run average.