How can my eyes be totally bad and totally good at the same time?

I am severely nearsighted. My spatial vision is extremely poor. For example, I can barely catch a ball. I usually have to stand right in front of bus timetables to be able to read them.

However, my eyesight is much better in other areas than others. I'm the only one at home who noticed that the TV was crooked. It really bothered me, but the others didn't notice at all. The spirit level proved me right.

But I also see stains on clothes much better than others, for example. Sometimes I don't even want to wear a sweater because I can clearly see the stain, and my family doesn't see it at all.

But how can it be that my eyes are so bad and at the same time so good?