How have the pigs changed the seven commandments? in Chapter 10. Animal Farm

The pigs changed the seven commandments in three important ways.  First of all, the seven commandments became one single commandment.  This single commandment did not sum up the original seven.  Rather, it "clarified" the seventh commandment.

"All animals are equal." became "All animals are equal, but some are more equal than others."

Also, unlike the original seven commandments, the single new commandment fails to distinguish friends from enemies, and even implies by omission that the pigs (who are now walking on two legs--a position previously used to identify the "enemy") are now, in fact, the "more equal" among the animals. 

Finally, the rest of the prohibitions listed in the seven commandments no longer exist, once again implying that these are no longer necessary since those in power (the pigs) can, through their status of being "more equal" have the right to do as they please.