Many Jews (especially those living in Christian countries) probably believe that the two tablets containing the Ten Commandments looked as something similar to the McDonald's symbol (two arched tablets, bond to each other) because this is how Gustave Doré (see this) , and even Marc Chagall ( see this ) among many other artists have painted them. There is no source for this popular image, and it actually seems that the Tablets of the Law looked more like the tablet which Lady Liberty is holding in her left hand: two square tablets, independent from each other . According to the Talmud Baba Batra 14a the tablets were rectangular, with no arc. They each measured 6 tefahim [=handbreadths. Each tefah is a little more than 3 inches] high by 6 tefahim wide by 3 tefahim thick.
In any case, this is just a visual and relatively minor non Jewish myth.
The major differences between the Biblical and the Christian tradition, which we will analyze BH in the coming weeks, are related to the content: for example, the way non-Jewish tradition reinterprets the prohibition of making images, or the observance of the seventh day. But before we analyze the major issues I would like to point to another popular misconception. According to Jewish tradition the Ten Commandments contain more that ten commandments. For Maimonides, for instance, the Second Commandment includes four precepts: The prohibitions of 1. believing in any god, other that haShem; 2. making idols; 3. bowing down to idols; 4. worshiping idols. Consequently, the Ten Biblical Commandments contain actually 13 precepts or Mitzvot, not 10.
What is more disturbing about this misconception is that the Biblical text never called the Ten Commandments "commandments" (i.e., 'eser hamitzvot) but debarim ('aseret hadebarim, or in Rabbinical Hebrew 'aseret hadibberot), which in Hebrew mean the ten "words, enunciations, proclamations".
Quoting Rabbi Hayim Pereira Mendes: "The Ten Commandments are called in Hebrew 'Asereth Hadebarim"-"the ten words or declarations." In English they are called "the decalogue," from two Greek words, deka ten, logoi, words."