@MathBgu I have read all above given answers, all are very informative one thing i want to add for your better understanding, by considering the formula of convolution as follows [![convolution equation][1]][1] 


and for the cross correlation

[![cross correlation equation][2]][2]


  [1]: https://i.sstatic.net/dDuTP.jpg
  [2]: https://i.sstatic.net/gpRwV.png
we comes to know that equation-wise the only difference is that, in convolution, before doing sliding dot product we flip the signal across y-axis i.e we changes (t) to (-t) , while the cross correlation is just the sliding dot product of two signals. 

We use the convolution to get output/result of a system which have two blocks/signals and they are directly next to each other (in series) in the time domain.