The most common form of laser level used for home DIY projects is a line laser level. The laser projects a line across the room's surface. This can be used, for example, to install furniture on the wall, assemble shelves, and process synthetic wood.A cross line laser level, as the name implies, will simply send cross laser lines across the room, which is ideal for hanging pictures or mirrors because you will be able to see if it is straight in line with both the ceiling and the wall. Some tiling works can also be completed with the help of these laser levels.See here: