The SFP 10G LR and SFP 10G LR S are both types of optical transceivers designed for 10 Gigabit Ethernet (10GbE) connections. While they share similarities, there is a key difference in terms of the supported distances and the types of fibers they are compatible with:  

1. SFP 10G LR (Long Range):

• Distance: Typically supports a longer reach compared to LR S.

• Fiber Type: Designed for use with single-mode fiber (SMF), which is optimized for longer-distance transmissions.

• Maximum Distance: The LR variant generally supports distances of up to 10 kilometers (km) or more.

2. SFP 10G LR S (Long Range Short):

• Distance: Intended for shorter-reach applications compared to LR.

• Fiber Type: Also designed for single-mode fiber (SMF).

• Maximum Distance: The LR S variant typically supports distances of up to 2 km.

In summary, the key difference lies in the supported distance. The "LR" variant is designed for longer-range transmissions and can cover distances of 10 km or more, while the "LR S" variant is optimized for shorter-range connections with a typical reach of up to 2 km.

It's important to note that these are general guidelines, and actual performance can depend on factors such as the quality of the fiber optic infrastructure and the specific implementation of the transceivers. Always refer to the product documentation or datasheets provided by the manufacturer for precise specifications and compatibility information.