What’s the difference between Brainiac, Superman’s enemy and Brainiac 5 from the Legion of Superheroes?

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What’s the difference between Brainiac and Brainiac 5?
What’s the difference between Brainiac, Superman’s enemy and Brainiac 5, the hero from Legion of Superheroes? Are they related? Is there a connection between them?

Why is Brainiac 5 good while Brainiac is evil?