Why do the Jedi/Sith have different color Lightsabers? Not compared against eachother.

Well, I dont know for sure, this is a guess. But "red" often represents " anger" or " evil", being mad. You heard of a mood ring well when your mad it usually turns red I believe. " Green" on the mood ring symbolizes being calm. And well you know the Jedi they tend to focus towards that mind set. And Blue is similar it means " normal/fine". But if you think about it alot of things that are evil are represented sa pamamagitan ng the color red. The Devil for instance is sinabi to be red or has been depicted that way. Hope I gave you an Idea at least.

Want to know something cool. off topic but Vader in German means father. Thats how Germans say father is " Vader". Ironic that he Became Darth Vader just as his wife gave birth to his twins.