What is orthographic distinctiveness? what does it mean when something is orthographically distinctive?

Question

how is lymph, khaki, afghan more orthographically distinctive than kennel, leaky, airway

Answer 1

Basically, weirdly spelled.
You'd expect kennel, leaky, and airway to be spelled the way they are (maybe leeky or areway) but you'd expect the others to be spelled limf, cacky, and affgan. "Y" is rarely pronounced "i" and "ph" is much less common than "f"; "kh" might actually be unique to "khaki", "k" doesn't usually occur on its own between two vowels and "i" is not usually found at the end of words.