Well, not exactly in that there are cultivars and farm differences. In that way it is a little bit like grape wine, where different processing can produce very different wines from the same grapes, but there are also differences in grapes that can come through within a style.
In a way, yes; Wuyi rock oolong will be different than a high mountain Taiwanese oolong. But what most people think of as green vs black tea, they don't realize that it's the same exact plant. Camellia sinensis has only 2 cultivars, var. sinensis (the main one) and var. assamica.
This is quite incorrect. Of the top 10 planted wine varietals in the world [0], all ten are red grapes to red wine or white grapes to white wine:
Top grape varieties by planted hectares
1. Cabernet Sauvignon - red grape, red wine.
2. Merlot - red grape, red wine.
3. Tempranillo - red grape, red wine.
4. Airén - white grape, white wine.
5. Chardonnay - white grape, white wine.
6. Syrah - red grape, red wine.
7. Grenache Noir - red grape, red wine.
8. Sauvignon Blanc - white grape, white wine.
9. Pinot Noir - red grape, red wine.
10. Trebbiano Toscano / Ugni Blanc - white grape, white wine.
There are some wines which are produced with red grapes which are not left on skins so there is no impartation of red colour, but they are really not common and the result is most of the time a bit closer to a light rose than what would be considered a white wine. Perhaps the only style that would be semi-frequently encountered are some French Blanc de Noirs wines, various champagne examples being the most common of these. (And of course standard champagne itself, but I am not sure if that is really considered a white wine). Still, rare. It is also not possible to produce a red wine with a white grape, there is no colour in the skin to impart.
