If we all saw everything the same it would be kind of a boring world. In fiction, if our characters all see things the same, well, it’s kind of boring.
People are different. That’s the beauty and tragedy and mystery and frustration etc…of people. When I’m writing, I sometimes find that my characters start to sound too alike-- or maybe just two of them who I identify with most closely with sound alike. This is not good. Characters need to sound distinct and be distinct. This means not just what they do and how they do it but how they sound when they think and talk.
I struggle with this sometimes. I suppose most writers do. One way to help make your characters more distinct is to focus on their flaws. If your characters don’t have flaws, then that’s a problem too. Most likely they’ll have different flaws, and if they do this might help you make them more distinct. Along these same lines you might think of one sort of major flaw of a character to help you develop that character.