3D printer technologies
FDM (Fused Deposition Modelling) / FFF (Fused Filament Fabrication)
The most common type of 3D printer out there. FDM is a 3D printing technique where material (usually a plastic filament) is melted layer by layer and fused together.
There are a few motion types that fall under FDM.
SLA (Stereolithography)
SLA printers use a laser to polymerize a photosensitive resin. They provide sharp details, at the cost of longer print times, comparable to FDM printers, since the laser has to follow a path to cover the whole layer.
DLP (Digital Light Processing)
DLP is extremely similar to SLA, except DLP uses a projector to flash an image on the platform, opposed to a laser beam.
The print time is much lower since the entire layer is exposed at once.
LCD
A subset of DLP printers is LCD-based printers. Instead of using a projector, LCD printers have a LCD display that masks a UV lamp.
SLS (Selective Laser Sintering)
SLS printers are usually very expensive and used in industrial contexts. Like SLA printers they use a laser, but instead of polymerizing a resin, the laser is used to melt powder.