The main difference between waxed paper and parchment paper is their respective coatings. Parchment paper is coated with silicone to give it a nonstick, heat-resistant surface, whereas waxed paper is coated with a wax such as soybean or paraffin.
Waxed paper is not meant for use in the oven—the wax coating on it will melt if the paper is exposed to direct heat—so use it for wrapping up sandwiches or food for cold storage. Parchment paper is the best choice for cooking, as most brands can withstand temperatures up to about 420 degrees Fahrenheit (double-check your package to be safe). Parchment paper is good for lining cookie sheets to eliminate the need to grease them, and is also used to cook “en papillote,” a technique of wrapping food in a packet and baking it (like in our recipe for Roasted Fish with Thai Pesto).
The other way the papers differ is in how they’re processed before being coated. Pat Schweitzer, a spokesperson for Reynolds Consumer Products, says that the company’s parchment paper is pressed into a sheet, then dipped into an acid bath, washed, and “passed over a series of hot rotating drums that realign the fibers and give the paper its strength,” before the silicone coating is applied. Reynolds’ waxed paper, on the other hand, undergoes a process called supercalendering, which compresses the paper to give it its transparency, before it is coated in wax.