From Bulbapedia, the community-driven Pokémon encyclopedia.
There are six known kinds of Team Rocket uniforms. There are black ones, worn by grunts, white, black and silver ones, worn by actual agents, and dark red and blue ones, worn by trainees. The trainee's colors show no difference in rank. While there has never been any official link between rank and uniform, the following are fan speculations of rank in comparison to uniform color and style based on the difference in treatment, behavior, and missions of the agents who wear them.
Types of uniform
The first kind of black uniform is worn by Team Rocket Grunts. The female grunt uniform is a simple black skirt with a large red "R," belt, long sleeves, and black knee length boots and black gloves that go up to the forearm. The male grunt uniform is the same except that it has pants and a shirt, instead of a dress and the boots only go up halfway to the knees. All grunts wear black hats.
The white uniform is worn by "B Rank" agents. Mondo wears this uniform, and Jessie and James wore this until Memories are Made of Bliss!, and then again in Battling For The Love of Bug-Types!. The male version seems to be a white version of the grunt uniform with a few alterations. There is a slit in the shirt and B Rank agents wear black shirts under their uniforms. They wear black gloves and boots. While the male version seems to have the same gloves and boots as the grunt uniform, the female has longer gloves, no black undershirt, and a knee-length skirt instead of pants.
The second kind of black uniform is worn by "A Rank" agents. It is worn by Cassidy, Butch, Jessie, James, Domino, and Miyamoto. It is similar to the black uniform worn by grunts, but instead of black gloves and boots, they wear white gloves and boots with a red stripe around the top. The female uniform has gloves that are nearly arm's length and boots that come up above the knee, it also has a red and white stripe on bottom. The male uniform also has a white belt and both have a white shirt or collar underneath the black top.
Domino's outfit seems to be an alteration of this, possibly denoting that her rank or at least duties (if not official ranking due to her young age) in Team Rocket is different than that of other "A Rank agents" which would be in line with her responsibilities and actions.
The silver uniform is worn by "A+ Rank" agents. Attila, Hun and Tyson wear this uniform. Although only male characters have been seen wearing this uniform, we have seen two different versions. It is unknown whether there is a (or perhaps two) female version(s) that we have not seen or if Hun is wearing the "female" version of the uniform. It seems that the former is more likely since all other versions of female Team Rocket uniforms except for the Trainee uniform have skirts that cut off above the knee, and the second silver uniform has long pants.
The first version of the silver uniform (worn by Attila and Tyson) has a sleeveless blue shirt with a silver vest over it, a black belt, silver pants and black boots that stop below the knee. The second silver uniform (worn by Hun) is a short sleeved shirt that cuts off below the chest, with a long sleeved blue shirt under it. The pants are long and flare out at the bottom, it is the only uniform where the boots are not worn over the pants. All silver uniforms have high collars that stick up.
The uniforms worn by trainees are identical save color, one is dark red and the other blue. In Training Daze Jessie and James wear the dark red uniforms and Butch and Cassidy wear the blue. There does not seem to be a difference in the trainee uniforms as far as gender is concerned. All trainees wear short black gloves and boots.