The Bible was originally written in several ancient languages: Hebrew, Aramaic, and Greek. When these languages are translated into English, there are often several different ways that a word or phrase could be rendered--this gives rise to various English translations. The same dynamic is at play with the new translation of the Roman Missal: we went from a dynamic thought-for-thought translation to a more literal word-for-word translation. The various translations of the Bible span the spectrum from very loose to very literal. By reading different translations from different parts of this spectrum, you can gain a better understanding of the original text. Linked here are a few of the more popular Catholic translations:
New Jerusalem Bible - a dynamic translation from the original languages
New American Bible Revised Edition - a mostly dynamic translation from the original languages
Revised Standard Version - Catholic Edition - a mostly literal translation from the original languages
Douay-Rheims Bible - a very literal translation from the Latin Vulgate