There are two English translations of the Bible approved by the US Conference of Catholic Bishops. The Revised Standard Version Catholic Edition is, by and large, the translation of Biblical scholarship and it is a “word for word” translation. The New American Bible is more of a “thought for thought” translation. The NAB will sound more smooth than the RSV much of the time.
What we hear proclaimed in Mass is the lectionary reading which is based on the New American Bible but will sometimes be slightly different. These word choices are determined by making it sound best when proclaimed in the assembly.
This graphic contains a helpful visual of where different translations fall. It’s also important to note that the USCCB does not say Catholics can’t use other versions. A variety of versions is often necessary to get at the underlying meaning. Just be aware that footnotes and even word choices in other translations may be influenced by different theologies that might not agree with Catholic theology.