lithium cells are primary (like those for cardiac pacemakers, calculators etc) while lithium ion and lithium polymer cells are secondary (these are otfen used in laptops and mobile phones)
i'm sure wikipedia would have more info. also try
http://www.mpoweruk.com/lithiumS.htm if you're doing the rechargeable cells (i did and the question popped up in my half yearly!)
i don't think it really matters which lithium cell you study, as long as you've got it covered in terms of the syllabus dot points you should be fine.