A dot laser emits only a dot, usually a dot laser has a plumb down, plumb up, and a horizontal dot at 90° to plumb up and down. Sometimes they have 3 horizontal dots at 90°, usually used indoors for partition fit-out, electrical light placement, sprinkler system layout, kitchen & cabinetry set-out and equipment set-up.
Typically used indoors, a line laser emits a line beam, usually one horizontal and a minimum of one vertical – sometimes four at 90°. With a beam of light transmitted to a surface (i.e. a wall) these are highly visible over distances to approximately 10 metres. With a line laser that has a pulse setting to pick up a line detector, these lasers can be used outdoors to 50 metres in some instances. Used for tiling, kitchen or cabinet set-out, electrical drywall setup, partitioning etc. Some indoor lasers can be a combination of a line and dot laser.
A laser with a diode prism that spins at faster speeds, these are typically used indoors or outdoors over longer distances up to 1000 metres diameter, dependant on the size of the laser diode. a detector picks up the beam and is usually mounted on a measuring staff. The rotating laser units mounts on a standard tripod. Some models can be turned on their side and emit a vertical rotating line. Some models allow either manually or automatically, a gradient or slope and some do this in two directions. This allows for an even slope over the entire workplace within the laser working diameter. Used for concreting, excavation, suspended ceiling set-up, landscaping, general building, levelling, earthworks etc. Generally the higher the unit cost, the more added features like gradient, scan, vertical etc. the unit will have.