Take steak for example. Cheap steak needs sauce. Good steak on the other hand is spoilt by sauce, a good steak tastes amazing on its own.

Take standard supermarket vegetables: nothing special there. Know someone who grows them themselves? Try them. Taste the difference? Suddenly vegetables are worth eating again.

Take a bad dessert: it's got all the right ingredients, but it tastes meh. You've just ingested half your daily calories eating meh. Now try a good dessert: omg how did they do this.

That's the difference.