Thanks for stating the [fairly] obvious.
...in brewing parlance, or at least HBT parlance, 2-row refers to the American 2-row pale malt (and the techniques and cultivars used therein), while Maris Otter refers to the English 2-row pale malt (and the techniques and cultivars used therein). Highlighting the fact that they're both 2-row -- or, indeed, reducing brewing malts down to a basic, physiological aspect of the plant they came from -- is akin to saying "Young's Double Chocolate and Guiness are both stouts, end of story."
(Putting on my own pedantic hat...) Maris Otter is such a unique strain that the malt carries its name. "Maris Otter" is not the name of a town or company, but the specific variety of barley used in its production. It's also floor malted, as opposed to kilned. All these things amount to a product that is notably different when compared to other 2-rows, or other malts in general -- which is why I asked the original question.
Yep, not to mention that had I read through the whole thread I would have seen someone else already posted the same info.