According to the World Health Organization, “Equity is the absence of avoidable, unfair, or remedial differences among groups of people, whether those groups are defined socially, economically, demographically, or geographically, or by other means of stratification. ‘Health equity’ or ‘equity in health’ implies that ideally everyone should have a fair opportunity to attain their full health potential and that no one should be disadvantaged from achieving this potential.”
Imagine the following: A new bike shop in town is giving away free bikes to everyone who attends their grand opening. Although you were excited to receive a free bike, after arriving at the grand opening, you learn that they're only giving away one model of bikes. Therefore, the majority of people can't safely ride the bikes they received, if at all. While the bikes were distributed to everyone (an example of health equality), it wasn't equitable because not everyone can safely ride the same size and type of bike.
Advancing health equity requires the assurance that everyone in a community has the opportunity to thrive and any differences in health that exist are because they are unavoidable rather than avoidable and rooted in social injustices. For example, first-born babies tend to have lower birth-weights than second-born babies. However, this difference is rooted in physiology with research showing links between birth order and gestational age, which then impact birth weight. On the other hand, racial differences in birth weight such as babies born to Black mothers typically having lower birth-weights than babies born to White mothers have been shown to be linked to stress from racism, an unfair and avoidable cause rooted in social injustice.