While we can use more specific terms like:

* Isotopes: Atoms of the same element with the same number of protons but different numbers of neutrons.

* Ions: Atoms that have gained or lost electrons, giving them a positive or negative charge.

The most fundamental way to describe atoms of different elements is simply by stating that they are different types of atoms. This emphasizes the core difference that makes them distinct: they have a different number of protons in their nucleus, which defines their atomic number and therefore their element.