A sensation is a type of feeling, picked up by one of the five senses. Peppercorns will give you the sensation of a million tiny pinpricks on your tongue.
A sensation is something from your senses. If you lose sensation in your feet, they are numb and it's time for you to get up and move around to restore blood flow. You can call something a sensation if it is wonderful and astonishing. Your parents will tell you that you were a sensation in the school play. Everyone will want to go see the special-effects movie that critics are calling a worldwide sensation.