What is the difference between an ion and an isotope?
I would say that one deals with the electronic configuration while the other with the nuclear one.
Consider two atoms of the same element. One of them can (for whatever reason) lose an electron. It is still that element but now it is...unbalanced…it is an ion.
Now consider the same situation, but with one of the atoms with an additional neutron inside its nucleus. From afar you'll say that they are the same but ...when you weight them...they are different.
Using a rather tragic example, consider two twins; we can say that a ion is one of the twins that has lost a leg…and now it is unbalanced while an isotope is one of the twins that got fatter!