I’ll be referring to the differences between the Hebrew Bible, Protestant Bible, Catholic Bible, Greek and Russian Orthodox Bible and the Ethiopian Bible. The New Testament is identical between all of them except for the Hebrew Bible. The Hebrew Bible (called the Tanakh) does not contain a New Testament. The New Testament is about Jesus Christ and the Jews do not recognize Jesus Christ as the Messiah.
The real differences lie in the Old Testament. The Hebrew Bible has 24 books and the Protestant Bible has 39 books. They contain the same content, but the difference is in the way some of the books are divided. For example, the Hebrew Bible has a book called The Twelve and the Protestant Bible divided that into twelve books about each of the minor Prophets (Hosea, Joel, Amos, Obadiah, Jonah, Micah, Nahum, Habakkuk, Zephaniah, Haggai, Zechariah and Malachi).
As for the other Bibles, we first have to look at how the Hebrew Bible was created. Over 2500 years ago, Rabbis started assembling the books to be considered for the Hebrew Bible. Several Jewish scholars spent over 300 years prayerfully considering which books belong in the Hebrew Bible. This process was called canonization. Finally, around 100 BC the Hebrew Bible was completed. During this time, around 250 BC, Pharoah Ptolemy II Philadelphus requested a Greek translation of the Hebrew Bible for the Library of Alexandria. You see Greek was the primary language in Egypt at that time. So, even though the Hebrew Bible wasn’t completed yet, 72 other Jewish scholars took everything being considered for the Hebrew Bible and included it in their translation, the Septuagint (which means 70). The books included in the Septuagint which were not canonized by the Jewish scholars were referred to as deuterocanonical and were included in what is called the Apocrypha.
The Catholic Bible, Greek and Russian Orthodox Bible and the Ethiopian Bible are all based on the Septuagint. Each of these selected different Apocryphal books to include in their Old Testament. That is why the Hebrew Bible has 24 books, the Protestant Bible 39, the Catholic Bible 46, the Greek and Russian Orthodox Bible 52 and the Ethiopian Bible 54.
The reason I chose the Protestant Bible (KJV, NIV) was that Jewish scholars who spent 300 years and Saint Jerome spent 23 years doing research, both decided that the Apocryphal books should not be included in their respective Bibles. Now those of you who know that Jerome was commissioned to write the Latin Vulgate (Latin translation of the Bible), also know that the Apocrypha was included. What you might not know is that Jerome was compelled by the Church to include the Apocryphal books in the Latin Vulgate. He made it very clear that he thought the Apocryphal books were not canonical books and should not be included. I am not opposed to reading any of the Apocryphal books, nor am I against anyone who has a Bible that includes the Apocrypha. It is their choice. God created us to use our mind to make informed choices. Although the Old Testament is the foundation, know that the New Testament teachings about Jesus is the same in each of these Bibles. Now, you get to choose.