Anti-Semitism is anti-Jewish bigotry and unacceptable. But anti-Zionism is simply being against Israeli policy and a legitimate political belief.
By definition, Zionism is the political dogma that insists on the creation of a Jewish state on land that belongs to Palestine. This operates as a political policy. Anti-Zionism is the opposition to this political policy. Anti-Semitism, by contrast, is prejudice against Jews.
The very definition of the words ‘anti-Zionism’ and ‘anti-Semitism’ describe two radically different concepts. It is like comparing apples and oranges. The Israeli state is not an automatic stand-in for all Jews across the globe, nor can it be treated as such. Criticising Israeli policy, therefore, is not tantamount to criticizing Jewish people. It cannot be accused of being anti-Zionism any more than criticising Iranian expansionism can be accused of being explicitly racist. One term refers to a political difference of opinion. The other refers to explicit prejudice and bigotry against the Jewish populace.
Anti-Zionism is simply anti-Semitism shrouded in publicly acceptable language. It is not socially acceptable to make slurs against Jewish people. However, criticising the state of Israel is far more palatable. As a result, often, anti-Zionism is simply anti-Semitist spouting their bile under the guise of criticising Israel. This is best illustrated by the language anti-Zionists use. Ilhan Omar, Malia Bouatta, among other anti-Zionists, are comfortable repeating anti-Semitic tropes and stereotypes in the name of anti-Zionism. Ilhan Omar played on anti-Semitic tropes in suggesting Jewish money controlled US politics. Malia Bouatta did the same when she suggested Jews controlled the international media. Both are anti-Semitic tropes and stereotypes. The fact they were repeated under the guise of anti-Zionism demonstrates the extent that anti-Zionists are just the anti-Semites of the modern era.
[P1] Anti-Semitism refers to prejudice and bigotry against all Jewish people. [P2] Anti-Zionism refers to political opposition to Israeli policies. [P3] The two terms refer to entirely different concepts. [P4] Therefore, they refer to entirely different things.
[Rejecting P3] They refer to the same concept: a prejudice against Jews. Anti-Zionism just expresses anti-Semitism in politically acceptable language.