Cations and anions are both ions. The difference between a cation and an anion is the net electrical charge of the ion.
Ions are atoms or molecules which have gained or lost one or more valence electrons giving the ion a net positive or negative charge.
Cations are ions with a net positive charge.
Silver: Ag+, hydronium: H3O+, and ammonium: NH4+
Anions are ions with a net negative charge.
Examples: hydroxide anion: OH-, oxide anion: O2-, and sulfate anion: SO42-