Location on the tea plant, mainly. Hyperpremium is the baby leaves; we only use the newest growth. Imagine baby vegetables, baby herbs, microgreens. They haven’t had much time to develop much molecular complexity, so there are no bitter or astringent notes, just clean, chlorophyll-packed umami. Leaves used for coldbrew are slightly older, and have a little more biocomplexity to them. That complexity does add some bitterness and astringency, but it’s undetectable when prepared with ice water, so it tastes rich and creamy. Yields are tiny for the hyperpremium, and yields are bigger with coldbrew (the leaves themselves weigh more, and are larger, hence bigger yields).