Individuality is the set of qualities that make one person (or one thing) different from all the others — the particular mix that makes you you. It is an uncountable noun, so you say 'her individuality', not 'an individuality'. People usually talk about individuality as something worth protecting: schools 'crush' it, uniforms 'hide' it, art teachers want students to 'express' it. Those are the verbs it lives with. There is a quieter use, too, for things rather than people: each handmade bowl has its own individuality; a neighbourhood loses its individuality when every shop becomes a chain store. Here it means roughly 'its own character, not mass-produced sameness'. Two neighbours are worth keeping apart. Personality is what someone is like — cheerful, shy, sharp. Individuality is the fact of being unlike everyone else. A person can have a strong personality and still dress and think like everyone around them; that person has personality but is not showing much individuality. Identity is a third neighbour: it is the answer to 'who am I, and what group am I part of', which can point outward to a group, while individuality always points away from the group.