And to add,Jupiter and Mercury belong in the same category as in they both orbit a star (the Sun in this case), both have enough mass to be spherical, and both have clear most of their orbits.

But the category of planets has sub-categories. Mercury is a rocky terrestrial planet while Jupiter is a gas giant as the former is smaller and rocky while the latter is large and made of mostly hydrogen and helium gas. Gas giants can also be called “Jovian planet”, but Jove is just an alternate name for Jupiter (the god) so you’re basically calling Jupiter a “Jupiter planet” which I think is a bit ridiculous but whatever it’s fine. Both are still, of course, planets. It’s like a large tree and a sunflower. Both are still considered plants, but certainly in different subclasses of the category of plant.

Dwarf planets, although not proper planets, are still very interesting objects that could even harbour life in oceans below their icy surfaces. Also, Pluto is not alone in the dwarf planets classification. There’s also Eris, Ceres, Makemake, and probably thousands more we haven’t discovered yet!