Can a character somehow gain more, or less, hit dice than they have character levels?

I find the wording of regaining Hit Dice during a long rest very odd:

The character also regains spent Hit Dice, up to a number of dice equal to half of the character’s total number of them (minimum of one die). For example, if a character has eight Hit Dice, he or she can regain four spent Hit Dice upon finishing a long rest.

, when it could have simply been stated that a character regains spent Hit Dice up to half their level, minimum of one. Is there some corner cases where a character can have more or less Hit Dice than they have character levels?