The Answer:

Putting aside differences in interpretation and translation (which could fill a library), various groups do number the Ten Commandments differently. Let's walk through them, using the King James Version of Exodus 20:1–17 for the sake of convenience. (Note that "Protestants" below refers to most—but not all—Protestants. Some use the Catholic numbering.)

• Catholics and Protestants: Preamble / Jews: First Commandment
• I am the LORD thy God, which have brought thee out of the land of Egypt, out of the house of bondage.
• Catholics: Beginning of First Commandment / Protestants: First Commandment / Jews: Beginning of Second Commandment
• Thou shalt have no other gods before me.
• Catholics: End of First Commandment / Protestants: Second Commandment / Jews: End of Second Commandment
• Thou shalt not make unto thee any graven image, or any likeness of any thing that is in heaven above, or that is in the earth beneath, or that is in the water under the earth: Thou shalt not bow down thyself to them, nor serve them: for I the LORD thy God am a jealous God, visiting the iniquity of the fathers upon the children unto the third and fourth generation of them that hate me; And shewing mercy unto thousands of them that love me, and keep my commandments.
• Catholics: Second Commandment / Protestants and Jews: Third Commandment
• Thou shalt not take the name of the LORD thy God in vain; for the LORD will not hold him guiltless that taketh his name in vain.
• Catholics: Third Commandment / Protestants and Jews: Fourth Commandment
• Remember the sabbath day, to keep it holy. Six days shalt thou labour, and do all thy work: But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates: For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.
• Catholics: Fourth Commandment / Protestants and Jews: Fifth Commandment
• Honour thy father and thy mother: that thy days may be long upon the land which the LORD thy God giveth thee.
• Catholics: Fifth Commandment / Protestants and Jews: Sixth Commandment
• Thou shalt not kill.
• Catholics: Sixth Commandment / Protestants and Jews: Seventh Commandment
• Thou shalt not commit adultery.
• Catholics: Seventh Commandment / Protestants and Jews: Eighth Commandment
• Thou shalt not steal.
• Catholics: Eighth Commandment / Protestants and Jews: Ninth Commandment
• Thou shalt not bear false witness against thy neighbour.
• Catholics: Ninth Commandment / Protestants and Jews: Beginning of Tenth Commandment
• Thou shalt not covet thy neighbour’s house, thou shalt not covet thy neighbour’s wife,
• Catholics: Tenth Commandment / Protestants and Jews: End of Tenth Commandment
• nor his manservant, nor his maidservant, nor his ox, nor his ass, nor any thing that is thy neighbour’s.

—The Editors