I get what you are saying, but surely their definition of "peace" itself differs quite dramatically. I venture to say they in fact are not after the same thing

I get what you are saying, but surely their definition of "peace" itself differs quite dramatically. I venture to say they in fact are not after the same thing, while they may be using the same words. Their use of the word "evil/not good" only serves as a distraction as that is a word used to determine how aligned or misaligned a subject thinks it or some other subject is on our or its way to whatever goal we have in mind, but this doesn't mean the goal is the same if two actors use that word. What Siths want is autocratic control for its own sake. If they could somehow have robots or whatever handle the galaxy's "peace", they wouldn't suddenly grab a martini and start relaxing on the beach singing beautiful songs of cosmic harmony. They would still exert control in their characteristic sadistic, vindictive ways. They are in it for themselves, they don't care about anything else and I'd argue they are incapable of knowing. They are wired that way. In a way it's sad. They want personal control and personal aggrandizement. When they use the word "peace" they mean "lack of resistence (to me)" and not "freedom from violence and liberty for all". Jedis fundamentally want a different thing. They don't want to become personal dictators over a faceless populace subjected to their every arbitrary whim. They do want "freedom of violence and liberty for all". They want an order based on rules and those rules must be born out of concern for life itself, not the indiscriminate use of power to get whatever the hell you want when you want it. That's why Siths are obsessed with personal power, not because their aims are equivalent. It's because their aims are not equivalent.