As of 10/17/24, there are 10 variants:
Wooden Scythe
Stone Scythe
Blackstone Scythe
Deepslate Scythe
Iron Scythe
Golden Scythe
Loose Redstone Scythe
Redstone Scythe
Diamond Scythe
Netherite Scythe
Wooden Scythe using any planks
Stone Scythe using Cobblestone
Blackstone Scythe
Deepslate Scythe
Iron Scythe
Golden Scythe
Loose Redstone Scythe
Redstone Scythe
Diamond Scythe
Wooden Scythes can be crafted using any planks (not including Mosaic planks)
Stone Scythes can be crafted using Cobblestone or Stone
Deepslate Scythes can be crafted using Cobbled Deepslate or Deepslate
Netherite Scythe
Like axes, scythes can be used to break most blocks derived or similar to wooden planks or logs, as well as a few other blocks. A scythe also uses 1 durability to break 1 block except for blocks that break instantly.