It's in the eye of the beholder, really. What do you find the most meaningful when distinguishing lucha: cultivar, manufacturing process, leaf grade/pluck, terroir...?
For example, I've heard "yunwu" used to refer to a category or style of teas. Now, does this refer only to a microclimate of misty mountain slopes, or are there other characteristics like leaf style that yunwu teas have in common? Is yunwu a useful classification, or is it simply a marketing term that gets thrown around a lot?
For teas like wulong and puerh, production is confined to a smaller geographic area, so a lot of variables line up in predictable constellations. E.g., 1) tieguanyin IS a specific cultivar, 2) IS rolled in ball-style, and 3) IS grown in a canonical area. You can oxidize/roast it several different ways, but it's still TGY. Change 3) by too much and it's likely to be called imitation TGY. Change 1) or 2) and it's likely to be called a completely different tea.
So, are we truly looking at a largely random distribution of all these variables in lucha? Are there patterns or correlations? If not, which variables are the most useful for making distinctions?
Every time I make a post like this I anticipate all the people who are thinking, "just drink it, dummy," and/or "no amount of book learning can substitute for tasting it." So let me reiterate that I agree that the taste experience is the ultimate truth, but I think learning some conceptual categories before/while tasting will give you "taste understanding" that you may never have gotten in a lifetime of drinking. And please consider charitably that this belief is a necessity for those of us who can't afford a jin of everything....