When to use linear or logistic regression? Still I have no clear concept when I should choose linear OR Logistic regression. 
 In addition, when I can say either linear or logistic regression performing better? 

In particular, I want to know When should I choose Linear Regression and When to choose Logistic regression?
Linear Regression is used for predicting continuous variables.

Logistic Regression is used for predicting variables which has only limited values.

Let me quote a nice example which can help you make the difference between the both:


  For instance, if X contains the area in square feet of houses, and Y
  contains the corresponding sale price of those houses, you could use
  linear regression to predict selling price as a function of house
  size. While the possible selling price may not actually be any, there
  are so many possible values that a linear regression model would be
  chosen.
  
  If, instead, you wanted to predict, based on size, whether a house
  would sell for more than 200K, you would use logistic regression. The
  possible outputs are either Yes, the house will sell for more than
  $200K, or No, the house will not.