There's quite a variety of workbenches in Conan Exiles and many of them have a slot for a thrall. Aside from adding some visual interest, the right thrall in the right slot can craft items that would not be available to you otherwise. For example Armorers from different groups (Stygians, Cimmerians etc.) will be able to craft you different types of gear, and Cooks will bring their own recipes to the Stove.
However, some benches don't have their own dedicated thrall type but can accommodate specialist thralls from other benches. The following is a list of workbenches in the game with the type, or types, of thrall that each can be assigned.
Most of the choices are fairly obvious, but a few are less so. For example, you might expect to put a Tanner on a Tanner's Table, and you can if you like, but you won't gain any benefit from this, the table will work as it did before. Instead, if you want to add extra functionality, such as being able to stitch together normal hides to make thick ones, you have to add an Armorer. It's slightly odd.
Alchemist's Bench (Alchemist)
Armorer's Bench (Armorer)
Artisan's Table (Tanner/Smelter)
Blacksmith's Bench (Blacksmith)
Campfire (Cook)
Carpenter's Bench (Carpenter)
Casting Table (Armorer/Blacksmith)
Dyer's Bench (Alchemist)
Fermenting Barrel (Alchemist/Cook)
Firebowl Cauldron (Alchemist/Cook)
Furnace (Smelter)
Saddler's Worktable (Armorer)
Stove (Cook)
Tanner's Table (Armorer)
Tannery (Tanner)
Tinker's Bench (Armorer/Blacksmith)
Torturer's Worktable (Taskmaster)
Wheel of Pain (Taskmaster)
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Inspired by this I just did a bit of testing and it appears that Artisan's Benches will actually accept any type of worker Thrall except Priests. There appears to be no advantage to any (unless they still provide a crafting speed increase, which they once did).