The General Rule
For the most part, Achievements are separate between the two platforms. If you want the Void Monk "Fists of Fury" achievement on both platforms, for example, you have to earn it on both platforms.
Leaderboards are synced each time you log into one of the platforms. If you win a council game on either platform, it shows up in the other when you log into that other platform.
On Steam, when your leaderboards are syncing and you are downloading your total wins, the game will unlock achievements related to any new wins that it pulls down. These are the Achievements affected by this:
- Academy Teacher - Win 25 Games
- Academy Master - Win 100 Games
- Old School - Win a Game with the Council
- Council Hero - Win 50 Games with the Council
- Own the Night - Win a Game with the Dark Elves
- Dark Elf Hero - Win 50 Games with the Dark Elves
- Short But Feisty - Win a Game with the Dwarves
- Dwarven Hero - Win 50 Games with the Dwarves
- Charge! - Win a Game with the Tribe
- Tribe Hero - Win 50 Games with the Tribe
- Vvvictory - Win a Game with the Team Fortress team
- Crazed - Win 50 Games with the Team Fortress team