Sancerre and Pouilly-Fumé are both Sauvignon Blanc wines from the eastern Loire Valley, but they come from opposite sides of the Loire River.
Sancerre tends to show brighter citrus, green apple, and a more lifted, mineral-driven profile, often from limestone soils.
Pouilly-Fumé is typically a bit richer and rounder, with more pronounced smoky, flinty notes, especially from its silex soils.
In simple terms, Sancerre is often sharper and more linear, while Pouilly-Fumé leans slightly broader and more textured.