I beat the game on normal now I was going through each mission and beating it on hard and I'm not getting the achievements. Do I have to start a new game because selecting each mission isn't working?

I don't know if you have to, but I started a new game on Hard and got the achievements after beating each level.

Can someone please tell me wtf GRAW is? I keep seeing it mentioned all the time but i honestly have no idea what the hell it is lol.

Tom Clancey's Ghost Recon: Advanced Warfighter

As for the hard, I did the same as above and started new on hard, sorry I am not much help.

I guess I'll start a new game I didn't think you would have to though. Game is not easy on hard but I guess that's why they call it hard.

It isn't much more difficult on hard, same number of baddies, only they take head shots now.

Nothing compared to COD2 on veteran.