Normative ethics deals with (surprise!) norms, which aren't necessarily what one might think. For ethics, a norm isn't some sort of statistical average ("taller than the norm"), but rather a standard or rule to which conformity is in some way expected.
Norms have an "oughtness". They include moral prescriptions like the Golden Rule, notions of etiquette like where to place a knife or fork next to one's plate, and sensible maxims such as "Look before you leap." But they also include some very non-moral things, such as rules about the order of operations when you're working math problems, or about not mixing types of units when calculating measurements (10 yards plus 10 meters does not equal 20 yards or meters), or even whether four-of-a-kind beats a full house in poker!
Metaethics, on the other hand, is where we talk about ethics (and norms). Instead of laying down rules about what is good or valuable -- the job of normative ethicists -- we ask, "what is 'good'?" and "what is 'value'?" We have to be careful not to use judgmental terms in metaethics, because they are inherently part of normative ethics, and we would risk introducing circularity (bad!) into our work. All we're allowed to use in our discussion of metaethics are descriptive and logical terms.
Now, here's a crucial point for my philosophy: I claim that comparative terms (e.g., "X is 'greater than' Y") are allowable in metaethics, being simple, logical comparisons of things we observe and describe.