Clothing stores are often in monopolistic competition with one another. This means that they will need to differentiate themselves from their competition. In order to do this, they need to convince consumers that they are in some way different from and better than the competition. There are a number of ways in which they might do this.
They might differentiate on the quality of their clothing. They might claim that their clothing is more high-end than that of their competitors. They might sell only certain brands that have a good image. They might be like Abercrombie and Fitch and try to market themselves as a brand that is only worn by “cool” people.
They might differentiate on price. A bargain clothing store would do this. They would say that they provide the best value at the lowest price.
They might differentiate based on their ability to help people who are hard to fit. Perhaps the most common example of this sort of thing is a “big and tall” store. Such stores tend to differentiate themselves on the basis that they are more helpful to people who are bigger or taller than normal.
All of these ways (and others) can be used by a clothing store to differentiate itself.