perhaps this is the most comprehensive web link i have ever read
http://www.psycom.net/depression.central.lieber.html
This is a good web site below, for more information but Iindahand is right,
Bipolar 1 is were you experience full blown mania episodes i think for more than a week eg, ( hyper mood, rapid speech, little need for sleep, erratic spending, increase sex drive etc) as well as depression episodes for more than 2 weeks, eg( low mood, sad, crying, decreased or increased appetite, sleep more or less than normal, no energy etc)
Bipolar 2 is were you experience hypo-mania which is like a mild version of mania ( how that is decided by the psychiatrist you will have to look up as i am not so sure. Bipolar 2 then also has depression just the same as bipolar 1.
now please any one correct me if i am wrong but i believe that to be right.
Also would like to say thank you for being a good friend who cares enough to look it up and be interested in your friends illness.
http://en.wikipedia.org/wiki/Bipolar_disorder
the web contains abundant information, here is only a few:
http://ezinearticles.com/?Bipolar-Type-2-And-Type-1---What-Is-The-Difference?&id=813439
http://www.webmd.com/bipolar-disorder/guide/bipolar-disorder-forms
http://www.webmd.com/bipolar-disorder/guide/bipolar-disorder-symptoms-types
http://wiki.answers.com/Q/What_is_the_difference_between_bipolar_1_and_bipolar_2
Bipolar 1 means you get full out manias, bipolar two means you get hypomanias. If you google mania you'll be able to get a full description. Maybe someone else will explain. I am feeling too down tonight to get into it more.