Deep eutectic solvents (DESs) are now widely acknowledged as a new class of ionic liquid (IL) analogues because they share many characteristics and properties with ILs. The terms DES and IL have been used interchangeably in the literature though it is necessary to point out that these are actually two different types of solvent. DESs are systems formed from a eutectic mixture of Lewis or Brønsted acids and bases which can contain a variety of anionic and/or cationic species; in contrast, ILs are formed from systems composed primarily of one type of discrete anion and cation. It is illustrated here that although the physical properties of DESs are similar to other ILs, their chemical properties suggest application areas which are significantly different.