The article did a great job in differentiating between both Sects. Just to add to the article Ali was not just called mawla, the actual statement of Mohammad (p.b.u.h) was "Whomsoever's master (mawla) I am, this 'Ali is also his master." Shi’ites believe that successor to Mohammad (p.b.u.h) cannot be chosen democratically as only perfection (Mohammad p.b.u.h) can know who’s perfect for succession.

For those willing to learn more about shi’ite: http://www.al-islam.org