This is headcanon, but I like to think both are Jedi outfits, but are from different sects/periods of Jedi history.

If you look at Count Dooku, his outfit is pretty similar to Luke’s ROTJ. They probably simply referred to Luke’s outfit from a production standpoint, but from an in-universe perspective, perhaps the black uniform was used by Jedi in the Old Republic that were more “Knight” than “Monk”. They may have been more intertwined with the government they represented than later Jedi, who chose to be somewhat separate to the government they served. These Jedi may have answered directly to a government leader rather than a Jedi Council, or may have been government themselves. In Dooku’s case, he was the Count of his homeworld, and leader of the Separatist movement. In Luke’s case, he may have simply found the outfit or doesn’t know the full history behind it beyond it being a Jedi uniform. Or maybe it could be intentional, since he is a military leader within the Alliance to Restore the Republic. At this time, Luke may have saw himself more as a warrior than as a monk. Maybe this look predates the reformation of the Jedi order and the Republic.

As time went on, perhaps the sects of Jedi who adopted the more religious trappings gained more influence in the Jedi Order as a whole, leading to the more monk-like, samurai look. In the High Republic, the Jedi had essentially beat the Sith, achieving a moral/cultural victory. Because of this, they wore more opulent robes of white and gold, conjuring the image of Catholic priests. But overtime, problems grew within the Republic and the Order. Maybe the Jedi saw their opulence as representative of their pride, so their uniforms became less flashy as they emphasized more of their Buddhist monk mentalities.

Obviously in real life they just made it up as they went, but it is fun to think about.