Playfield itself is the left side of the screen, where all the balls are. There are 6 different Play Fields in Q-Lat 2. Every Play Field has a bit different laws of physics than the others. In some the balls move faster, in some the friction is smaller. In some they accelerate faster etc. Some Play Fields have more realistic laws of physics, and some do not. Each Play Field has it's own distinctive color.

Control Panel is located at the right side of the screen.
From the Control Panel you can see
you're score,
the remaining time,
and your bonus color.
You can also change your current control method (mouse or keyboard) by clicking the icons on the Control Panel. An icon with a picture of keys changes control method to keyboard, and an icon with mouse changes your control method to mouse.
Alternatively you can use M-key as a keyboard shortcut.
New in version 2.2:
Now you can choose a game pad to be your game control by clicking the icon with a picture of a game pad. A small number on the icon tells which game pad (1 or 2) is chosen. If you don't want the game pad to be selected, click the icon again. After this the other player can choose the pad (if there is only one).

Besides that the balls can have different colors, the balls come in 3 different sizes as well: small, normal, and big. Moving around with a big ball is bit different than moving with a small ball.

Grey balls, unlike other balls, are not affected by friction, so once they start moving, it's difficult to stop them. Try turning them to some other color. And I recommend you do it before they start moving :)

On occasion a random ball on the field turns to gray. Watch out, it could be you :)

New in version 2.2: Balls with a face texture have a nasty habit of moving around randomly by them selves. How much these balls move depends on the difficulty level and the chosen play field.

Bouncers: An obstacle on the field. If a ball touches the Bouncer, it will be hurled away with great speed... Kind of a flipper like thing...