The main difference is the level of carbon content, 316 stainless steel has a 0.08% max carbon content while 316L has a 0.03% max carbon content. Since SS316L has a lower carbon content than SS316, SS 316L stainless steel wire is softer than SS 316.
The ”L” in 316L refers to the extra low concentration of Carbon in the steel. The reduction in carbon content helps to prevent an effect called “sensitization”, where carbon combines to chromium, reducing the chromium-free content.This allows the steel to be welded without the formation of potentially weakening carbides.
316L is low carbon with 0.03% maximum to prevent the loss of corrosion resistance caused by chromium carbide formation during welding. 316 is 0.08% carbon maximum. Neither grade has a specified minimum carbon content. The strength requirements for 316 are a little higher than for 316L.
Another different at minimum yield strength of type 316L (170 Mpa) is less than 316 (200 MPa).