Which Bond is stronger : Ionic or Covalent Bond ???

In general, ionic bonds are easier to break, but it depends on several factors. For instance, breaking ionic bonds is very easy to do when you dissolve an ionic compound in water. Water is special because it effectively reduces this Coulombic attraction between the plus and minus charges on the ions (it kind of acts like a barrier or shield, blocking the plus from seeing the minus). However, if you were trying to break an ionic bond in a perfect vacuum, it would be much harder (because without something to block the attractive force, it is quite strong). Another thing to consider is that ionic compounds usually form 3-dimensional crystals, where there are many many ionic bonds, whereas covalent bonds tend to be found in isolated molecules (except for network covalent compounds like diamond or silicon). The fact that ionic bonds form a 3-D structure in a crystal makes a huge difference. So part of what makes this question so complicated is that you kind of comparing apples and oranges.