Based on the answer provided here, it seems to me that when the word "equity" is used in relation to "equality," an equal outcome is necessary in order to differentiate between equity and equality. Otherwise equity would just be equality.
I know that there are good arguments against achieving equal outcome, so the alternative must be that I am missing something in the definition of equity.
Edit: The definition of equality used in this question pertains to societal treatment of people.
Your question supposes that equity and equality have precise meanings, which is not true. Words mean what people take them to mean, so you might take the word equality to mean something subtly different from the meaning I associate with it. However, equality tends to be used to mean treating people in the same way, whereas equity means fairness. You can see the difference in lots of circumstances. Consider golf, for example- to give everyone a fair chance of winning a game, there is a handicap system, which means that players are not treated equally, but weaker players are given a leg-up against stronger players.
So:
When there's equality, there's no need for equity, if you pay more to women for the sake of equity, and according to its conditions, you are assuming women are less worthy, that they are not equal to men, which seems absurd. Equity is necessary when there's no equality.
It is the market that defines the outcome, not the buyer, not the seller (not men, not women alone). So, it is not men that pay less to women. Women also pay less to women. Women don't attend (and pay for) feminine basketball matches. Women pay more to men. At least in basketball and STEM jobs. Think who is paid more in non-STEM jobs (bricklayers, constructors, etc). I believe seeing statistics about the market paying more to women in jobs involving emotional intelligence (communications, some forms of team leadership, etc.), which I imagine is a substantial part of non-STEM jobs.
So, the market assumes a priori that there's equality; therefore, equity is granted by default.
In general, the term equity is not used. Because there is equality, we live all in the same nature.
If you say that women in technical careers need to be paid more (this example is intentional: statistically, women earn less in technical careers), you would be implying that "women worth less". And they don't. They probably earn less just because in order to be a good technician, you need your full time and focus in life, which is easy for men. Women have the natural potential to have kids and breed them, which is a survival trait, which evidently changes priorities.
* Equality means identicity because you-now are identical to you-five-seconds-ago. Even when every atom in your body has changed, millions of particles have been evaporated, etc. Identicity is a human rational ideal between two states, what in thermodynamics is called macrostate. We feel the same temperature, because we assume that the energy has not changed (1st law), while internally, the microstates are constantly evolving. In such sense, men might not be identical to women (gametes are different on each sex), but surely we are equal.
See your own example picture: men get the larger bike due to its size. You can make the equivalence between bike size and salary, rider size and potential. You never give more salary to less potential. You pay more for more potential. Gender is not even considered in the equation.
The crux of the difference is;
A) a society of equality would treat all people the same.
B) an equitable society would treat all people based on each individual’s needs and to provide the same utility to everyone.
In the first panel of the image below, equality is depicted as everyone getting the same bicycle.
The second panel depict equity, where each person is given a bicycle tailored to their needs.
This is a rhetorical difference, not a concrete philosophical statement. I find it similar, but not quite as eloquent as John Rawls’ “Justice as Fairness”.
Terminology
- The Three Stations in Society: “The best off”, “The median”, “The worst off”. By setting up his thought experiment always as 3 outcomes of birth, he eliminates the concern for statistical outcomes based on population size and degree of inequality.
- The Veil of Ignorance: The initial position that everyone begins in, before the providence of the their birth is decided.
In Rawl’s thought experiment, he seeks to deliver a sufficient counter-argument to the rationale that supports the theoretical values of Utilitarianism. To do this, set up the following thought experiment:
Premise 1: All societies exist with a varying range of the distribution of resources, therefore all societies can be observed based on how well off the population is in regard to the Three Stations of Society.
Premise 2: The station of one’s birth is always equally random between the three options. While behind the Veil of Ignorance, there is no way to determine one’s station.
Premise 3: While the stations of a society are constant, the degree of inequality can be influenced by social priority of the society.
Conclusion: A rational, non-gambler would certainly choose the society that gave them the best odds in the worst case scenario, which would favor a society that provides the best life for the worst off person.
In the last consequence it comes down to how they are used and defined, by the person using them, in a particular context.
Theoretically they both apparently originated from the same Latin origin of "equal" or aequus which apparently just means "level" or "flat" and it's derived aequalitatem which means "equality, similarity, likeness". As can be found here for equal, equality and equity.
So apparently the meaning of the word for flat just got expanded and used in various contexts. Like flat, became "even, level or uniform". Uniform also invokes ideas of similarity and/or identity and sameness. While "equal treatment" and "treating each other as equals" (of the same (equal) value) is a core concept of justice.
And as these words entered the English language through French at various times apparently different facets of the word got associated with equity and equality where apparently tons of internet articles make it their point to define "equity as justice" and "equality as sameness".
That being said if you take a closer look at all these examples of where the "clear distinguishable difference" between equity and equality is presented, you'd essentially see that they still talk about something being the same. They just differ on what that is. Like if you frame this: https://ell.stackexchange.com/a/277988/152794 not as "everyone getting the same box", but as "everyone getting assistance to see the game" then the assistance that they got clearly is not equal from the perspective of the receiver, despite being equal from the perspective of the giver. And if you ask a neutral observer whether they see sameness or difference they'd likely would be confused and ask "with regard to what?". Like some things about each picture are equal some aren't.
So the problem isn't that one refers to sameness and the other doesn't, but that they differ in terms of what value they want to be the same. And what value they refer to crucially lies in the eye of the beholder. Like "equality before the law" is both the epitome of justice and fundamentally unjust when considering this famous sarcastic quote "The law, in its majestic equality, forbids the rich as well as the poor to sleep under bridges, to beg in the streets, and to steal bread." highlighting that "equal laws" apply to different people (or rather people in different situations) quite differently and not necessarily just.
There are other attempts to go around that problem by calling one "equality of outcome" and the other "equality of opportunity" but that's also mostly a farce as life is continuous motion so the outcome of one event sets the opportunities for the next and vice versa.
So within a particular context it can make sense to avoid the inherent ambiguity of "equality" by addressing that you want "this kind of equality not that" and by calling one "equity"="justice" and the other "equality"="sameness", but that still comes down as to how that person defines "justice" which can differ from case to case.
So I'd be skeptical of attempts to treat these two as catch all terms that hint you at the meaning in a universal sense and would still urge you to look at how they are used in the specific context.
