I remember reading of it when I started home brewing.
Top fermenting ferments at the top. Bottom, at the bottom.
One was supposed to achieve something, and the other was supposed to achieve something different.
My beer tasted like shit either way.
I liked the pilsiner story, where the wort had to be heated with red hot rocks dunked into the wort. The hot rocks caramelised the suagars in the wort, creating a pilsiner.
Never got around to that, as my beer tasted like shit.