Alkali: All anions ionized in solution (or molten state) are OH- (hydroxide ion).
Salt: Both anions and cations ionized in solution (or in molten state) are salts. You can remember that in inorganic substances, acids, bases, oxides and salts are produced.
Generally speaking,
The only cation in an acid is hydrogen ion.
The only anion in alkali is hydroxide ion.
For example, the commonly used baking soda NaHCO3 is a kind of salt, which is an acidic salt. It contains bicarbonate ion: HCO3-
There are metal ions and acid radical ions in the chemical formula of salt.
It should be noted that there should be
Acidic ions, such as Cl-, NO3-, SO42-, PO43-, etc.
CaO, for example, has metal ions, but no acid radicals, so it is not a salt, but an oxide.
The main acids are HCl, H2SO4, HNO3, H3PO4 and CH3COOH.
Alkalis mainly include NaOH, Ca(OH)2, KOH, Ba(OH)2, etc.