LED tiles come in 500mm X 500mm sizes. The number of horizontal and vertical tiles will determine the aspect ratio of the screen. The common aspect ratio for consumer televisions is 16:9. If you are using the screen for IMAG or video playback, you will want your screen to be 16:9 to avoid stretching and cropping.
With LED panels the sky is the limit regarding configuration. You can also use them as set pieces and spread them out for creative stage designs.