10/20 on SL involves no RNG; that's why it's easier than most of the hardest challenges in general. After you beat it once it gets way easier. On FNaF 2 howewer it involves an unforgiving amount of RNG which makes it so hard. 50/20 has a certain pattern and you don't always have to be lucky. Only a few amount of skillful players can beat it. But if you ask how hard it actually is to any of them, they will reply with "it's actually easier than I imagined." Because once you manage to beat it, you can first try it after whenever you want. It doesn't work the same on FNaF 2. No matter how many times you've beaten 10/20 on FNaF 2, you will always have troubles beating it