I had a Islamic extremist explain to me the difference between an Anti-Zionist and Anti-Semitic. He said that he loved his fellow Jews. That he had nothing against them, it was those that were trying to force Arabs out and kill them. Ask any of these extremist and they'll tell you Zionist consist of more then just Jews. They consider a lot of American politicians to be Zionists as well, who AREN'T Jewish. So you can be jewish and not a zionist and you can be a zionist and not a jew.
There's also different types of Zionists as well. They all want Israel back to what they believe is thier natural borders (though they all seem to have different ideas of what those borders are). The difference is some just want it to happen with the 2nd coming of the messiah, where as the extreme ones want to FORCE that coming by taking back the land through force, thus bringing about the second coming. At least that's how I understood it, and how it was explained to me. Don't get me wrong, I'm not for any extremist group that feels to need to kill other people to fulfill their agenda, political or religious but I do feel that these extreme Zionists have to be look at in the same light as extreme Islamics.