1,422 word pairs that get mixed up, in three kinds: words that sound identical, words that look almost identical, and words that mean nearly the same thing. Each comparison puts the two side by side — pronunciation, part of speech, senses, and which of the two you are more likely to meet.
Six letters or more, differing by a single character at least three letters in. The constraint matters: without it the same method returns beach and reach, which nobody confuses.