Selective laser sintering (SLS) involves an entirely different approach. Like SLA, it uses a laser, but of a higher power and used to fuse together fine powder. Direct metal laser sintering (DMLS) and selective laser melting (SLM) are similar techniques but are optimized for metal and alloys instead of thermoplastics. SLS works primarily with nylon, polystyrene, and other polymer materials.
The main strength of SLS prints are their superior strength and durability. Additionally, they can be of complex geometries that are not possible with SLA (or FDM). While SLS can produce prints of greater detail than FDM, they generally don’t compare to the precision of SLA.
Because of their highly powered lasers, SLS machines incorporate more advanced technology, including special shielding against harmful UV radiation. This results in printers that are more expensive, with few desktop or benchtop options available.
Furthermore, SLS 3D printer powders are more expensive than liquid photopolymers.
In a nutshell, if high mechanical strength and complex shapes are your priority, and the cost is of minor importance, use an SLS printer. Otherwise, SLA 3D printer is probably your best bet.