There is a custom for men to wear a Kittel, a special white robe, on the High Holidays and at the Pesach Seder. Also, a Kittel is one of the traditional Jewish burial garments. The same word is used for both; are they identical garments? Does a person get to designate a Kittel for use in the grave, or is there a standard one provided by the burial society?
They're similar, but not necessarily identical.
I've heard in some German communities, the groom is presented with his burial shrouds as a wedding present by his in-laws elect! But usually today, what I heard from someone in a Chevra Kadisha (Jewish burial society) has a bunch of standard garments. They recite the verse about the Cohen wearing his garments (ksones bad kodesh yilbash ...) as they dress the body.
The Gemara says Raban Gamliel instituted using the simplest possible garments, as the costs of Jewish burials had gone out of control. Many wedding kittels today are made fancy, and I think occasionally contain synthetics. Burial garments need to be simple, and made of natural fibers.
The Netziv, in the introduction to his Haggada (Imrei Shefer IIRC) mentions that some think we wear the kittel on Seder night (Passover) as a "downer", reminiscent of burial shrouds; he outright rejects this idea.
It's actually not a universal custom (even among Ashkenazim) to use a kittel in burial. R' Yechiel Michel Tykoczinski, in his Gesher Hachaim (27:4), writes that the custom in the Land of Israel is specifically not to do so, as there is a specific number and list of pieces of clothing used for burial shrouds that should not be changed.