The term "catholic" is an adjective as well as a noun. "Catholic" actually means "universal" and was used early in church history to refer to the church as a whole. "Catholic" is also a noun commonly used to refer to the western Roman church which split from the east in what has come to be called the Great Schism.
Orthodox are not Roman Catholics and Roman Catholics are not Orthodox. The Roman church in the west (Rome and beyond) has evolved since the schism while the Orthodox have remained virtualy unchanged. Roman Catholic doctrines and practices today more closely resemble Protestants.
Orthodoxy has never experienced events such as the Reformation or Counter Reformation, but has maintained the fullness of the Gospel message since long before the additions that crept into the Roman Communion, such as the doctrines of Papal Infallibility and the Immaculate Conception. The Protestant Reformation has also greatly erred by accepting many of Rome's practices, such as the filioque clause in the Creed, while jettisoning many of the hallmarks of what the Church really is, such as the Historic Episcopacy of the Bishops. Almost all Protestant denominations owe their origins to the Roman Church's evolution through the filter of the Reformation.
Orthodoxy means "Right Thinking, Right Belief, Right action". Orthodoxy is the original church with unbroken unity and succession. Within it is contained the Faith of our Fathers and the original teachings of the Apostles.
[* Journey To Orthodoxy NOTE: After further research, I have discovered that, although the definition "universal" in reference to "catholic" is commonly used, it was a later development and is not accurate. "Catholic" actually means "wholeness" or "fullness" and is more accurately used to infer a spiritual state rather than a geographical one. ( JTO 7/26/07)]