If you are dreading something, it doesn't mean that you are afraid or scared, it just means that you are really, really not looking forward to something. I am afraid of the tiger: I'm scared ! I am dreading going back to work after my holidays: I am not scared or afraid, I am just not looking forward to it.

Colloquially, the words are basically synonyms. "Fear" is much more common in everyday speech and covers a wide range of emotions: - It is not healthy to live in fear. - He has a fear (is afraid) of flying. - I fear the patient may not recover. "Dread" is a strong fear and has a sense of being afraid of something in the future: - I dread tomorrow's exam because I did not study for it. - I dread the outcome of this year's election. - I dreaded going to the dentist until I learned there was nothing to fear.