Avatar: Magic is limited to the four elements (and some spirit stuff). Furthermore, everyone except the Avatar is limited to at most just one element.
The magic battles are spectacular displays of creativity where each element is utilized to its full potential in a variety of ways.
Harry Potter: Magic is basically limitless, with there being a spell to do pretty much anything and any wizard can learn it, including an instant-death spell.
Which is why fighters on both sides only ever go for the best and most effective spells (Avada Kedavra for bad guys, Expelliarmus for good guys) and magic battles look like this:
I know what you’re talking about. With the most obvious example being Spiderman vs. Superman.
Spiderman’s powers being basically the same for 60 years now, and writers had to come up with new ways for him to use his abilities.
While Superman (especially in the silver age) is pulling new powers out of his ass at every given opportunity.
But I think unlike Harry Potter where there’s no reason for wizards to use anything except their go-to spell, Superman does use the full array of his powers to deal with different foes.
He doesn’t instantly go for freeze breath or heat vision every single time, even though they’d probably be the most effective powers for most situations.
I recommend reading Brandon Sanderson’s essay on his Second Law of Magic, in which he talks about one of his guiding principles when building magic systems: that the limitations are more interesting than the powers. He actually talks about Superman and how the limitations on his powers are what make him a good character, and talks about the Wheel of Time, which has a similar system to ATLA. It’s a long essay, but well worth the read if you’re at all interested in world building.
Here’s the link to his First Law and Third Law as well. The third law especially touches upon some of the concerns/criticisms brought up about HP and Superman.
