Thank you for asking the question! A lot of the people who don't know the answer to the question, just assume that FLDS and Mormons are the same people. Although I am not LDS and in fact I am not a Christian, I am very often troubled by the stereotypes that people have about LDS, and I am especially troubled when people make assumptions without checking the facts. Your questions indicate that you are the type of person who checks out the facts first before forming a conclusion.  
I can't answer from an LDS perspective to give you details about how the Mormons are different from FLDS. So, I can only answer from my own perspective.  
 
1. The Catholic Church at one time was the main Christian church, and most Protestant churches are offshoots from the Catholic Church. This includes Baptist, Lutheran, Methodist, COGIC, Foursquare, Pentecostal, etc. Of course, if you asked "aren't Catholics and Pentecostals the same people?" then Pentecostals AND Catholics would probably feel offended, because they are so different and they don't even want anyone to THINK that they are the same.  
I think its the same regarding FLDS and Mormon. In fact, as the Mormon church grows, I expect there will be many offshoots just like there are many major religions now that are offshoots of the Catholic religion.  
The recent news about the FLDS situation has caused me to reflect on the years when I didn't know much about Mormons but I THOUGHT I knew plenty. Now that I've spent years learning everything I can about Mormons, I realize that I was once very ignorant but it hadn't stopped me from making all kinds of ill-informed statements and judgments. I came to this askmamormon.com website, in fact, because I feel very depressed and guilty about my former ignorance and I am seeking ways to "repent".  
So, again, thanks for the question!