Looks like you obviously knew the answer to your question when you asked it. And it seems like it's more of an important distinction to you than to me and James, since we both knew what we were talking about!Salt based?
Chemists use the word salt quite differently. For them, a salt is any molecule that is made up of two or more ions. Sodium chloride (NaCl) is made up of two ions; sodium and chlorine. Ammonium nitrate (NH4NO3) is also a salt and is made up of an ammonium ion (NH4) and a nitrate ion (NO3). Potassium chloride (KCl) is common in fertilizer and is made up of a potassium ion (K) and a chlorine ion (Cl). There are hundreds of different salts.
As a solid, the ions join together to form crystals and chemists call these salts. When salts are dissolved in water, the ions in the salt separate and are no longer joined together. They are now properly called ions, not salt. This may seem like silly semantics, but it is an important distinction for properly understanding the effect of salts on soil and plants.