I've been reading Capital off and on for months and this is a seemingly pretty important difference that I don't understand. Is there a difference between surplus labor and profit, and if so, what is it? Any explanations, links, or chapters in Capital I should check out are appreciated.
— Marx's opening statement to "Volume 4" of Capital, Theories of Surplus Value
There is a difference between profit and surplus-value. It can be summed up pretty much as follows: