For me.... I think the difference between advice and judgement is the difference between empathetically telling someone what to do and telling someone what to think/feel.

For example:

Problem: My best friend put the moves on the girl I like and now they are dating. He even knew I liked her and pursued her anyways! I want to get back at him! What should I do?

Advice: I understand that you are feeling heartbroken and betrayed right now, however revenge is not the answer. Getting back at your friend will not erase the past. Evaluate your friendship with this person and decide if they are someone you still want in your life. If so, maybe a break from them is in order so that you have time to heal.

Judgement: You're acting like a child. Now you have learned the value of going after what you want right away. Next time, don't let your fear get in the way again. Quit being so jealous and try to be happy for your friend.