Not the WHM questline, but it's the level 25 CNJ quest line where two 'fairy' type elementals appear to help the player. It basically shows that the 'proper' elementals have gone quiet following the Calamity, and that the FFXI-style 'sprites' now commonly seen are just formless elementally-aspected aetherial energy created as a result of the Calamity which have no actual connection to the fairy-style elementals. So yeah, the two types are mutually distinct.