Here is an excerpt from an interesting article in the
Jewish Virtual Library:
The biblical texts display considerable similarity to the standard Masoretic (received) text. This, however, is not always the rule, and many texts diverge from the Masoretic. For example, some of the texts of Samuel from Cave 4 follow the Septuagint, the Greek version of the Bible translated in the third to second centuries B.C.E. Indeed. Qumran has yielded copies of the Septuagint in Greek.
The biblical scrolls in general have provided many new readings that facilitate the reconstruction of the textual history of the Old Testament. It is also significant that several manuscripts of the Bible, including the Leviticus Scroll are inscribed not in the Jewish script dominant at the time but rather in the ancient paleo-Hebrew script.
A considerable number of apocryphal and pseudepigraphic texts are preserved at Qumran, where original Hebrew and Aramaic versions of these Jewish compositions of the Second Temple period were first encountered. These writings, which arc not included in the canonical Jewish scriptures, were preserved by different Christian churches and were transmitted in Greek, Ethiopic, Syriac, Armenian, and other translations.
Some of these are narrative texts closely related to biblical compositions, such as the Book of Jubilees and Enoch, whereas others arc independent works-for example, Tobit and Ben Sira. Apparently some of these compositions were treated by the Qumran community as canonical and were studied by them.