From left to right.
1) A jumpsuit introduced on DS9. Currently in use aboard U.S.S. Voyager. This uniform did not replace the uniforms from TNG, but seems to have been used alongside it, as seen in Generations. Officer's on Earth still use the Next Generation uniform. 2) An admiral's uniform from the first season of TNG. 3) Dress uniform used from TNG's first season, up to the present. 4) Standard uniform used in TNG's first and second seasons. It was then used by extra's in the third season. 5) Uniform used from the fourth season, to the present. 6) Men's uniform used by main characters, from the third season of TNG, to the present.