Vertigo is commonly caused by a problem with the way balance works in the inner ear, although it can also be caused by problems in certain parts of the brain.
Vertigo makes you feel dizzy but it's caused by other things instead of just moving around etc.
Being dizzy usually just happens because of spinning around, standing up too fast, getting a lack of sleep etc.
Vertigo can happen even when you get enough sleep or don't spin around or move.