In Q-Lat2 there are 3 levels of difficulty: Rookie, Normal, and Guru. The higher the difficulty level is...

...the faster the game gets.
...the more bonuses there are on the Play Field.
...the more points you get when you turn a ball to the same color as your own.
...the more often a random ball turns to gray.
...the more Bouncers there are on the Play Field.
...the more often some bonuses appear (e.g. X, Freeze, Clone Ball)
...the longer your ball stays freezed after collecting an F-bonus.