Is your definition of "do good in the world" approximately equivalent to "donating to effective charity"?

No, not at all. Donating to effective charity can be highly important; but I'll be sad, and think something has gone badly wrong, if e.g. CFAR's altruistic impact occurs exclusively or even mainly through causing such donation; it is important to increase generators of knowledge of what is actually worth doing (rather than e.g. creating copies of CFAR's founders' initial beliefs on that subject), to increase people capable of finding important gaps in the world and then filling them, etc.

At the same time, donating to effective charity is both high-impact enough, and simple enough, that I suspect something will have gone badly wrong if we don't also see a lot of giving of that sort -- it'll suggest an unwillingness to take risks, or to trust others, or to pool together into common efforts, or something similar. I have actually a lot of thoughts on how the above point and this one can both be true, but the subject is a bit unwieldly; I may write a post; in any case, I agree with your nonequivalence.