Why do we feel like we need to classify the type of activity we do?

For example, the superficial difference between rock climbing and “bouldering“.

Or, the difference between “hiking” and “mountaineering“.

The same thing in the realm of photography; is there a real difference between “Street photography”,“ urban photography“, or “life photography”? Or the more silly difference between “street photography“ and “street portraits”?

Also, does it matter for there to be a difference whether the street photo were shot with permission, or without permission?