Whats the difference between Vegetable and Olive oils?!

No. Olive oil is healthier. Vegetable oil is best for frying fast because oil absorption should be less for it isn't as good as olive oil. Olive oil is also a little more expensive. Olive oil is good for cooking and comes from only olives unlike vegetable oil which is extracted from many different vegetables....(unknown veges) and is basically junk food.

When using oil to fry you also need to consider the smoke point of the oil. Smoke point is the temperature when the oil starts to break down (and therefore won't taste as good). If you need to cook something at a higher temperature then you may not want to use olive oil because it has a lower smoke point then other oils.

The point made about the flavour of olive oil is also an excellent one. You don't always want whatever you are making (for example salad dressing) to have olive oil as the dominant flavour. It would make more sense to use either a lower grade olive oil (not virgin or extra virgin) or a more neutral oil like canola.

Olive oil will give a distinctive taste to food, so there are some situations where you wouldn't want to use it depending on your preference.

I personally like the taste of olive oil and use it quite a lot.