Yes olive oil and vegetable oil can be used interchangeably since they're both vegetable oils but the difference is in how healthy one over the other is and the taste difference.
Olive oil has a different taste than vegetable oil so if you're cooking something that you want to get the best taste out of the food without having another flavor added to the food you're cooking.
Vegetable oil has very little extra taste to it so when you want the food tasting like it should then use the vegetable oil instead of the olive oil.
But when you don't care about the taste of the food you're cooking then you can use either olive oil or vegetable oil when cooking the food.
Olive oil is the more healthy version of cooking oil than vegetable oil so if you need a heart healthy oil then use olive oil.
I cook all my foods using olive oil and I find the taste to be just great in all foods even though the recipe calls for vegetable oil.