The illustration above pictures a situation in a city with snow, and two characters: the older man with his red hat and scarf, and the child with yellow hat and cloves. Now, what is real?
The photos from the old man depict memories of situations in the snow, maybe with his son? Building a snowman, skiing, walking the dog in the mountains. How would he perceive the situation? He might think it is a nice day.
The photos of the toddler show something different. Sun, sea, warmth. And she is standing in the snow asking to be picked up. How would she perceive the situation? Probably not so positive
Now, what is real? Is it real that we have a city covered in snow, with a temperature X and a time of day Y? Is it real that it is a wonderful day (the old man) or is it real that it is a terribly cold day (the toddler)?
We can measure the temperature, but is it cold? We can see how many people are in the street, but is it crowded? We can track the time it takes to walk to a nearby cafes-hop for a nice hot chocolate, but does it take long? If it takes 10 minutes, is that long? If you are carrying a toddler not enjoying the snow, would that make it long?
There is a difference between what we can measure and how these measurements relate to us, i.e. what we experience. James Gibson invented the word Affordances for this.
Especially in product design one challenge is to understand what is real for the user. Tools like personas, user journeys, interviews and shadowing help get a glimpse.