Zionism certainly differs from that of being Jewish as it's basically a political movement as opposed to a faith or race of people. I also have contention with the way the term "anti-semitism" is continually utilized to stifle any negative comment against Israeli government foreign policy. Certainly, both sides in this issue can be faulted for past transgressions but as you eluded to, one has to wonder why the US and Canadian governments clearly support Israel's position. When the Palestinians fight back, it is an act of terrorism but when Israel retaliates, it's considered a "measured response". Sound familiar?
Anti-semitism is also a rather spurious claim because many other ancient and modern races, including some Muslim groups as well as Anglo-Saxons, were descended from Shem (one of Noah's three sons in the Bible) and therefore could rightfully hold claim to being "Semitic". Conversely, not all Jewish ancestry can be traced back to Shem, but to the other sons Ham and Japheth.
It's clear that the neo-cons that dominate the Bush administration are the most rabid supporters of the creation of a Greater Israel along with the confinment of the Palestinians in isolated ghettos along the West Bank and the Gaza Strip.
Israel’s takeover of land it has occupied for nearly 40 years is in breach of international law and in defiance of countless United Nations resolutions and is even being denounced by several Jewish groups, including the following two from Canada and the US respectively:
We, Jews of Conscience, demand that the U.S. government:
1. Require Israel to stop its brutal siege on Gaza and on Lebanon and call for an unconditional cease fire.
2. Require Israel to stop the expansion of the Israeli Wall of Separation, dismantle the completed sections, and completely withdraw from Gaza, the West Bank and East Jerusalem.
3. Support the United Nations resolutions demanding that Israel uphold international law and support the sanctions against Israel necessary to enforce these resolutions.
4. End military and economic aid to Israel.
5. Support reparations for the Palestinian and Lebanese people for the death and destruction they have suffered and for aid towards the rebuilding of their countries.