I hadn't thought about how often we confuse these terms until I had a discussion about it today. Inequity is not the same as injustice.
In many ways, I am not equal to Bill Gates . . . certainly in terms of income or financial worth, and not in terms of speech either, since the Supreme Court has equated money and speech. But is my inequality with Gates an injustice? Of course not.*
We decide a base level of what is just and unjust. That base level could be equality . . . could be, but shouldn't be.
I wouldn't mind a little more money, but I certainly don't need as much cash as Bill Gates. I'm not sure I would even want that much money. Similarly, there are people who don't need or want as much as even my own modest financial worth.
Confusing inequity with injustice complicates any discussion of working toward justice in our culture - is absolute equality what we really want? Is it really even possible? We need to parse out our standards for justice with clear heads.
Or, to again paraphrase George Orwell, bad language leads to bad thought.
* Well, that money = speech thing is bullshit, but that's another discussion.
How a person gets achieves his financial worth is also a different discussion, and that could swing back to a just/unjust discussion. I use the example of Bill Gates advisedly here: I don't think that his methods of accumulating wealth are particularly unjust, though many feel his manipulation of markets is unfair, which again is not a direct parallel to unjust.
You can anticipate that this is a precursor to a discussion of capitalism and justice. I don't have any plans to post that discussion soon: it's a question that I have been and will be considering for a long time.