My impression of male Chareidi Jews is that they only ever wear a white shirt with a black suit shoes and hat, no tie. I also get the impression that particular other (possibly Chassidic) groups have a uniform which they all wear. Please correct me if I am wrong.
Why do they do this? Is there something wrong with looking different in their culture? Does the particular ensemble have significance or is it just a common expression of sober, severe dress?
At certain times and in certain countries Jews were required to wear certain articles of clothing. Rather than fighting these decrees, these became proud status symbols of the Jews who wear them.
Today dressing a certain way is an expression of allegiance towards a certain sect. Ie., a Gerrer chassid has different dress than a Belzer chassid.
Modesty is a law that applies to both men and women. Among the many aspects of modesty is the idea to be inconspicuous. If everyone is the same, then no one is attracting attention.
I believe that the dictum "don't separate from the community (Avos 2:4)" also has a part to play. Uniform is a way for the entire community to express their unity.
According to kabbalistic tradition, men should wear white clothing. However, the Rabbis explain that a side effect of wearing all white is that it engenders haughtiness. Black clothing is said to elicit humility. It could be that the black/white uniform is a result of this idea.