What is the difference between 4:3 and 16:9?

The number 4:3 and 16:9 refer to the aspect ratio of the projector. This is the relationship between the height and the width of the image. 4:3 is the traditional aspect ratio for television whereas 16:9 is a widescreen format. Check which size of TouchIT Board you have, the 78″ & 90″ are 16:9 and the 80″ is 4:3