Oh my, where did you get this from? I happen to know both. The founder of Scientology was a scientist who started with a somewhat decent idea, got popular in the US, but his fame passed quickly. He really craved for that fame, though, so he changed his teaching into some cultist stuff, paired with some sketchy lord and proceeded with demon invocations. His main book is Dianetics, and his followers are very vindictive to those who leave the cult.

Falun Dafa, on the other hand, is more like a Buddhist discipline. You are free to meditate in a park if you feel like it, you are free to go if you don't. There is no organisation, no one will know your name. Its main book is Zhuan Falun, which you could read to make your own opinion, rather than repeating someone's talking points. CCP hunts Falun Gong because its founder refused to become a part of CCP. You can read this story on Wikipedia. The situation is similar to the early days of Christianity when Nero burned christians alive and wanted to eradicate their faith. The irony is that today the Roman Empire has reduced to the city of Vatican which is the temple of Christianity. CCP will fall similarly.

As for organs extraction... well, read about the Sujiatun Concentration Camp. CCP sends there young Falun Gong followers and sells their organs to high rank officials. Demonic creativity. But what did you expect from a communist regime?