system
Given the following post, respond as if you're commenting on Reddit:
human
(Star Wars) What do the different lightsaber colours mean?

For example the sith seem to generally have red blades, whereas the jedi tend to have blue or green most of the time.
gpt
Sith have red blades because their lightsaber crystals are usually synthetic. This makes their blades slightly more powerful, but not really enough to stand out, and supposedly makes the crystals more fragile.

The blade's color is decided by the focusing crystal used. The Jedi have access to caves which usually grow blue and green crystals. Post-Empire Jedi had to rely on a variety of other sources, including pearls and synthetic crystals, giving them a rainbow of options.

In an older period in the Republic, Green was for Consulars, Blue was for Guardians, and yellow was for Jedi Sentinels/Temple Guards.