I've always wished for a little guide when entering the aged gates of Mea Shearim in Jerusalem (one of the oldest neighborhoods in Jerusalem outside of the old city, populated by Haredi Jews, established in 1874) to spot the different sects. Here are some interesting different groups and the differences in their dress.

Chabad wear the Prince Albert frock coat instead of the traditional bekishe and black fedora.




Ger wear their pants tucked into their socks (not breeches though), a round felt hat, and pointed kippah, and on Shabbis married men wear the shtraml or spodik (tall round fur hat, similar to shtreimel but tall, thin, and cylindrical).



Toldos Aharon men wear a white-and-grey zebra-striped coat during the week and a gold bekishes (caftan coat) on the Sabbath. They are the only group that requires a boy who is bar mitzvah at 13 to wear the gold coat and shtreimel along with the married men. They also wear a white kippah. Considered one of the strictest groups, girls of this sect wear pigtails if they are unmarried. Also their rebbe, Rabbi Aharon, decreed that they cannot wear wool at all for fear of mixing it with linen, which is forbidden by halacha.

Skverer men wear knee-high boots with their breeches on Shabbis, concealing their stockings. The Skverer rebbe and his family wear them everyday.

Additionally, most Chassidic men wear a gartel when they pray. It is a thin black belt with fringe (white ones are used on special occasions, like a wedding, when a man wears a special white garment). In halacha (Shulchan Aruch O.C. 91:1), a physical divider between a man's heart and genitalia is required during prayer. The rebbes insist that a regular belt will not suffice and there must be something that specifically divides the body into the lower parts and the upper parts, exerting control of the animal instincts with human intellect.

Lastly, Orthodox men wear tzitzit, white threads that often hang out of men's clothing. Sometimes there is one blue thread in each one. This comes from Bamidbar (Numbers) 15:38 -- "Speak to the children of Israel, and bid them that they make them fringes on the borders of their garments throughout their generations." To fulfill this, men wear a tallit katan, an undergarment that has fringes on the four corners. Chassidic boys receive them on their third birthday. Some groups wear them under the shirt, while other groups wear it over an undershirt but under the main shirt. (Side story: my father was giving a talk to a group of Christians one day and this woman came up to him afterward with scissors. She was about to cut the "string" he had hanging off his pants until he stopped her!)