Here's the definition from Internet Encyclopaedia of Philosophy:

Plain Consequentialism is a theory about which actions are right. Its standard is high. It says that among all the very many things we could do at any given time, only one or a very few of them are right. The implication is that the rest of them are wrong. So if your action does vastly more good than what most other people would do in similar circumstances, but you could have chosen an action that would have done even a little more, Plain Consequentialism says that what you did was morally wrong. Plain Scalar Consequentialism is different.

Plain Scalar Consequentialism: Of any two things a person might do at any given moment, one is better than another to the extent that the its overall consequences are better than the other’s overall consequences.

SC seems to me like the only plausible version of util (certainly far more sensible than the maximising/satisficing alternatives) on any sensible epistemology. Anyone disagree? I found one essay claiming to reject it, which I haven't had a chance to read yet, but from the abstract it sounds as though the author's a nonconsequentialist using this to have a stab at The Enemy.

It looks to me like SC is normal consequentialism, and Plain Consequentialism is that with the added idea that the right action to take is the morally best one.

It always seemed to me like the natural way to view it, but (at least according to non-consequentialists) it doesn't seem to be the default. The usual formulation seems to be a binary setup where one act is right and everything else is wrong.

Doing something the best way would be ideal.

Look at it this way. Suppose you're doing a complicated math problem on a test. Plain Consequentialism is like saying that the right answer is doing the problem right and getting the right number at the end. SC is like saying that the fewer mistakes you make the better. They're not mutually exclusive, and they're not really different versions of utilitarianism. They're just different ways of looking at the same thing.

That's not necessarily true. A typical definition of consequentialist theory of action I've seen is this:

An act is right iff it produces the best possible consequences.

Alastair Norcross has been writing a bit on how silly this is, which is what the essay above is criticising.

I agree with you completely Areppo. I've always been amazed at how most utilitarians speak in terms of what is obligatory, permissible and the one Right action. Unfortunately I don't have enough knowledge about the history of modern moral philosophy to know the answer to why it is so common. Perhaps it is because the influece of a tradition of deontology or the standard formulations of deontic logic (this is speculation).

I'm not sure if it makes a different in practice. But I've always considered the idea at best distracting and at worst repugnant. It seems a lot more useful to focus on relative moral goodness rather than which action is best, unless you are a deontologist that is. Also, it seems to me that using such a framework fosters deontological intuitions and facilitates arguments against utilitarianism.