But when we say your opinion is just that, you classify it as a fact.
One gives an opinion, such as: "I like the Manga".
A fact would be that at the end of part one, Naruto goes to train with Jirayai.
Someone else says Naruto goes to train with Kushina.
I point out that is false.
Of course, the statements are far less elementary, but often other people's opinions are backed by misinformation and false statements. Those that aren't, I respond to completely differently.