Both of these confusions are common enough to be considered fallacies. Respectively, they are called Equivocation and Distinction Without a Difference. They can also both be understood in terms of our earlier discussion of analogy, for in many ways they commit the same errors, only at a more abstract level. Equivocation occurs because we attach too much significance to a superficial similarity between words or expressions, viz., that they are spelled the same way. Distinction Without a Difference occurs because we attach too much significance to a superficial difference between words or expressions, viz., that they are spelled differently.
Equivocation can occur most easily when a certain word or expression has two or more meanings.
If you tell me that you just bought a new house, I will probably ask you whether the house is brand new, or an older home that is just new to you. If you think about your favorite riddles or jokes, you will probably find that some of them are funny because they momentarily confuse two different senses of the same word or expression. Equivocation is particularly difficult to detect when the meanings of words differ in subtle ways. We say that a person is discriminating if they are capable of recognizing subtle differences, or if they have particularly good taste. But now suppose I know a woman who can tell just by looking at people from diverse racial backgrounds precisely what their racial ancestry is.