[SFD-discuss] What does "Software Freedom" mean?

Hi, we are still trying to understand how to translate "Software Freedom Day" to Spanish, so let me ask another question: What does "Software Freedom" mean or refer to? I understand "Free Software", I'm just not sure how that's different from "Software Freedom", and if it's the same thing, why isn't the event called "Free Software Day" then? (providing an answer to that question would help a lot with translating it properly) Thanks! Marcelo