Assalamu alaikum,
The difference of the two would be from the origin, but what are the distinct belief or culture that would definitely differ the one from the other?
It's important not to group all the Shi'a as one, as there are different sects and groups within Shi'ism, and many lay people are not aware of what their leaders actually believe. More details are in the links above.The main differences is that they regard us as hypocrites, fake etc... for not following imam Ali just like they do. Also, they don't believe Quran is preserved which is something that constitute disbelief and they say that they're true Muslims.... and yet they dare to even challenge us for debate while they're liars??