What is the difference between a COD and a COI?

COD is complement d` object direct, while COI is complement d`object indirect.
COD:
-it is the word that responds to the questions: qui (who) and quoi (what)
-example 1: J` ai mis le livre sur la table.
          "Qu`est-ce que j` ai mis?" "Le livre".
           "Le livre" is thus a COD. 
-example 2: Pierre aime Anne. 
          "Pierre aime qui?" "Anne".
          "Anne" is thus a COD.
COI: 
-It is the word that responds to the question: a qui, a quoi, de qui, de quois
-example 3: Je lui telephone.
          "A qui je telephone?" "A lui."
         " A lui" is thus a COI.
Les pronons personnels COD:
me/te/le/la/nous/vous/les/les
Les pronons personnels COI:
me/te/lui/lui/nous/vous/leur/leur