CPR and BLS both are important part first aid training. I got my fingers crossed while differentiating between the two. After diving deeper down I found that both are too much coupled to each other that many people refer it as same but there do exist a slight difference among them.
To begin with CPR it is abbreviated from Cardio Pulmonary Resuscitation, it is applied when a person gets a sudden cardiac arrest by this method a first aid of chest compression by hands is given to the patient to restore the cardio vascular function in combination with rescue breaths if person is not breathing properly.