Open the scoreboard in-game. By default you'll accomplish that by holding the Tab key. You can click on any player to view their info, weapons and achievements. An example can be seen here:
Doesn't that just show the achievements that the player has gotten? He wants to know what all of the achievements are even the ones he doesn't have.
The tab menu shows achievements that are yet to be unlocked, they have a lock next to them. As for the hidden ones, they're hidden. So no, I'm not telling you