In my Golden Book Encyclopedia that I owned as a child, I read that a Belgian hare is NOT a hare, but a rabbit. I swear that the illogic of that statement started me on a road where discovering the differences between similar things got thwarted. (BTW, here’s the answer. Or HERE.)
Likewise, I’m not good distinguishing frogs from toads, monarch butterflies from viceroy butterflies, many car models (unless they’re really distinctive, such as the old VW Beetles, or a Rolls Royce), and even similar flowers.
I also must be somewhat colorblind, for I have a bear of a time distinguishing between black and navy blue, which I discovered about 15 years ago, when my mother bought me a blue chair to go with my blue rug. “What blue rug?” I pondered.
For what do you find difficulty in differentiating, particularly things that other people seem to see?