How do you tell the difference??

[Masco73]

I just bought a lot at a yard sale of colecovision carts(pics later in the finds thread). It came with the atari expansion and some atari games. I got q-bert in the lot and was wondering how to tell if it is atari or coleco version?? Can you tell visually or will I just have to pop it in to find out??

[Pantechnicon]

Look at the front edge (opposite the label side) of the cart. If the sides are perfectly rectangular then it's an Atari 2600 game. If the sides form a wide hexagonal shape then it's a Coleco cart. That's it.