One is French and the other widely used in the Balkans and Middle East, but there's more nuance to the differences between these two versatile pastry doughs than that. Sure both are many layered (unlike the traditional pâté brisée that we use in so many of our recipes), but puff pastry and phyllo are not interchangeable. If you compared the two, phyllo would look like a sheaf of tissue paper while puff pastry would seem much thicker, more like regular pastry dough. Substitute one for the other and your baked goods may bake up different than expected. Here’s a closer look at these two doughs.
Known as pâte feuilletée in French, puff pastry is made by rolling out pastry, placing a square of butter inside it, folding the dough and then rolling it out and folding again, repeating these steps to create contrasting layers (and layers) of butter and dough. Though you can't really see the layers when the dough is made, when it's baked those folds produce separate airy, flaky layers and a crunchy exterior.
You can make puff pastry but many cooks opt to use frozen puff (check the label to make sure it’s made with pure butter and not another type of fat). Puff pastry is used for sweets, from tarts to cookies, and savory dishes, from breakfast to dinner.
Phyllo consists of tissue-thin sheets of dough. The sheets are almost as thin as leaves; phyllo spelled filo or fillo means "leaf" in Greek. In contrast to puff pastry, phyllo dough has almost no fat, it’s mostly flour and water and can dry out easily. Ususually each sheet is brushed with melted butter before baking. Phyllo gets crisp and flaky when baked but it doesn’t have the same rich, airy quality that puff pastry has. Most recipes call for store-bought phyllo dough which is available frozen in grocery stores and occasionally fresh at Greek markets.
Phyllo is used for savory dishes, like the classic spanakopita or these individual Eggplant Feta Phyllo Pies, and for dessert recipes like the famed baklava found in Greece, Turkey, and other Middle Eastern countries as well as for dessert cups and crusts.
Watch the secret of working with phyllo dough: