Even though it was said earlier in this thread, I'll repeat:
- Yggdra Union (not Yggdrasil) is developed by Sting. It's being published/localized in the US by Atlus.
- Yggdrasil Labyrinth (not Yggdra) is developed by Atlus. It'll be published by Atlus.
The two games are as related as Valkyrie Profile, Vanguard Bandits, and Vagrant Story.