What are the most common symptoms of Bipolar Disorder? (In relation to depression.)?

What differentiates depression from Bipolar Disorder? I would really appreciate professional views! I could Google it, but I want a straight comparison; perhaps even from somebody that has/is still experiencing either of these. How did you come to recognize that you had Bipolar Disorder/depression? Any other information will be greatly appreciated. Just curious. Thank you. http://bit.ly/nJvwJF