ARGGGGHHHH, I'm confusing you, right? Let's take an example. Two cars collide on a Pakistani street, something really common. One incident, one reality. The two drivers will disagree and present their own version of reality. But there is only one "true" reality. One side note: both drivers could be arguing for a false version of the reality.
Why does this happen? Bias! All of us have our biases, no matter how neutral we may claim to be. Our biases make us perceive reality differently. Enough philosophy. Let's leave it at that.