Good question.
I think the difference between someone who loves himself and someone who does not love himself is this:
The person who loves himself both notices and appreciates his positives. He also makes sure to take care of all the things that affect him, such as his health, his finances, his faith, his social circle, etc.
The person who does not love himself will be reckless, bringing danger and insecurity into his life. He will allow himself to be ruled by addictions, habits, fears, etc.--especially if it he is able to obtain instant gratification for something. For example, he will overspend on a hobby and will not have enough money to pay for his apartment. He will also tear himself down more than he lifts his spirits.