Judaism refers to the Jewish faith, while Zionism defines the philosophy behind an exclusively Jewish state: the physical and spiritual homeland meant specifically for the Jewish people. You can be a Zionist as a Jew, but not all Jews are Zionists.
There are many Jews all over the world, and most of them reside in Israel or America. Zionists are hardcore. They tend to lack compassion, and they are quite rigorous in their beliefs. Judaism means living by the rules of the Jewish holy book, the Torah. Judaism is a religion that commits to its people, and there are not any ulterior motives or hidden agendas. Judaism is a simple way of life.
Zionism, on the other hand, speaks exclusively of the Jews. This form of Jewish practice is interested in the lineage of the Jewish race, which is separate from others. The Jewish people have suffered persecution because of their race. The Zionists do not support their kind, as they tend to be ignorant about the Jewish people.