Q: What is the difference between Orthodox Jews and Reform Jews?
A: Orthodox Judaism is the traditional variety which take the Scriptures literally and rabbinic tradition very seriously. They are very strict and exacting in the observance of the Torah as interpreted in the Talmud and later Jewish scholars. They also keep such traditional beliefs as a literal Messiah, a literal restoration to the promised land, and a literal life after death.
The Reform movement began in Germany in the 19th century with Jewish intellectuals who felt the old beliefs were no longer tenable. The reformers sought to reshape Judaism into a modern religion. Many of the doctrines which the orthodox took literally were spiritualized in Reform Judaism. They saw no need to expect to return to Eretz Israel -- "This is our Promised Land," "This is our Jerusalem." The expectation of a Messiah gave way to a humanistic striving to bring about a Messianic Age. Instead of viewing the Bible as the infallible word of God, they saw it as "the record of Israel's consecration to God." They had services in German (or whatever the local language was) instead of insisting on Hebrew; and they shortened the services.
They declared that ritual considerations such as keeping kosher were no longer relevant. The new Judaism was essentially "ethical monotheism." Some even went so far as to move the Sabbath to Sunday. The pendulum could only swing so far before coming back somewhat, however, and Modern Reform Judaism holds Sabbath services, uses at least some Hebrew, and encourages keeping the Jewish feasts as being important for Jewish continuity.