Speculation (if it's clearly marked as such) - is just an "entertainment" piece - for example, you could write in your blog what are the next features for iOS w

Speculation (if it's clearly marked as such) - is just an "entertainment" piece - for example, you could write in your blog what are the next features for iOS without any clear sources - that would be just speculating about. Fake news - news that has wrong info as facts or provide something as sourced when the original source never said that. I think that's rather huge difference (speculation from some outsider can still by chance be true, fake is by definition false)