When William came over to England he still spoke French, and he made French the official language of the courts. Because of this there are still words in English that are like the French, and sometimes a word is different in different contexts.
For example:
Pig is used for the animal. (it's like the dutch word for a baby-pig: biggetje)
Pork is used for the meat. (porc in French)
This is because the French would only use the word for what they were eating.