Both villagers and zombie villagers support setting a variant based off the minecraft:villager_type registry. However, only villagers support copying this component from an item stack with the minecraft:variant/villager component.

Steps to reproduce

1. Run the following command: /give @s minecraft:villager_spawn_egg[minecraft:villager/variant=swamp]
2. Place the villager spawn egg
3. Observe that the spawned villager appears to be a swamp villager
4. Run the following command: /give @s minecraft:zombie_villager_spawn_egg[minecraft:villager/variant=swamp]
2. Place the zombie villager spawn egg
3. Observe that the spawned zombie villager appears to be a plains villager