We all get hugs, but we don't pay much attention to them. Believe it or not. They can deliver a ton of information and great Body Language. Here's a few examples. Add yours.
*: Remember those.
Usually the hands would be on the shoulder, bodies wouldn't be touching or either hug from the side.
Bodies would be touching, you would either feel her breasts, without pulling her. If she holds tighter then you do, she's interested. Her hands might wonder around your back.
I'm sorry Hug:
Would look a lot like the friendly hug, they would rub your back or put your head on their neck.
Its not hard to tell if you've hugged a crying girl (You should). They would hide they're faces on your shoulder or lay their heads on yours.
*Hug from behind:
This is playful and also means that she can't wait to be alone with you.