Much has been written about the relatively minor differences between the Aseres Hadibros given by Hashem in Parshas Yisro and those repeated in this week’s Parsha. Some of the commentaries add beautiful thoughts and reasons for these distinctions. Nevertheless, we cannot lose sight of the fact that in something as significant as the Aseres Hadibros, each word, each letter requires the utmost concentration in study and analysis so that any slight changes are not glossed over or Chas V'Shalom, lost on us.
In the final commandment, Lo Sachmod, there are three such changes. First, in this week’s Parsha we are told initially “not to covet your neighbor’s wife and not to desire your friend’s house”. (Vaeschanan, 5:18) In Yisro however, we are first told not to covet your neighbor’s house and then not to covet his wife. (Yisro 20:14) Further, in this week’s prohibition an additional instruction of “not desiring” is added to the already existing one of not to “covet”. Finally, in this week’s Parsha, an additional example of things we shall not covet is added to the list of house, wife, servants, donkeys, oxen and all that he has. Specifically, in this week we add “his field”. Relatively small differences but significant, nonetheless. What is the Torah trying to tell us with these subtle changes?
In order to appreciate these variances, it is important, as always, to take in the context and the audience to whom the commandments were addressed. In Shemos, Bnei Yisroel were just recently taken out of Mitzrayim. Their most important focus was on becoming individuals again, with their own material processions, instead of slaves. Hence the emphasis on your neighbor’s “house”. Indeed, the mepharshim point out that the men in Mitzrayim were so worn out from their hard work as slaves that their wives had to go out into the fields to entice them to have children. It's no wonder that coveting their neighbor’s wife was relegated to second position. This is born out all the more by the inclusion in our Parsha of not coveting his “field”. Only now, as Klal Yisroel was preparing to enter Eretz Yisroel and have land of their own, was this specification germane.
There is a profound lesson here to be absorbed. When B'nei Yisroel left Mitzrayim, their existence as slaves until then left them with almost nothing to covet. Developing a sense of self or identifying possessions was what was desired. Now, after 40 years of having their daily needs taken care of by Hashem, their minds were freed to wander about other more expansive wants. Therefore, they were cautioned against more base and more deplorable thoughts. Human nature is such that the more we have, the more we want. We need not give in to this destructive instinct. Quite the opposite. By simply taking time to appreciate what we have we can counter this most base of instincts. We all have good in our lives. We also all have challenges. Every day we need to appreciate what we have and take the time to enjoy and bask in it, instead of looking at what is in someone else’s basket.
 The Ramban distinguishes coveting from desiring in that coveting means actually taking certain steps to acquiring that which one wants whereas desiring is just the thought of the acquisition.