[1] The key difference is that the positions of the cation and anion constituents are reversed in the unit cell structure.
Whether a compound will form an antiperovskite structure depends not only on its chemical formula, but also the relative sizes of the ionic radii of the constituent atoms.
This constraint is expressed in terms of the Goldschmidt tolerance factor, which is determined by the radii, ra, rb and rx, of the A, B, and X ions.
Antiperovskites naturally occur in sulphohalite, galeite, schairerite, kogarkoite, nacaphite, arctite, polyphite, and hatrurite.
The physical properties of antiperovskite compounds can be manipulated by altering the stoichiometry, element substitution, and synthesis conditions.