The similarities between these two games are that you have absolutely no control over the outcome. Every play is statistically and mathematically designed to extract money from players for the benefit of the house. They will let you win 2 games and then you will lose 3. They know that repeated players of this type of game will keep on feeding money back into the system because they get a rush from the wins and they conveniently forget all the losses. Any "technical" aspect to these games is purely an illusion, adding extra features into the game lets the player feel like they have a degree of influence over the outcome and disrupts the play enough that they keep trying to unlock things like mini/side games.