A slurry is a mixture of equal parts cornstarch to water. The water is whisked with the cornstarch to make a thickening agent. A slurry acts like roux and can be used in thickening soups, stews, sauces, and gravy.
Bechamel is a milky white sauce flavored with an onion pique, nutmeg, spices and a butter, flour mixture called a roux. Bechamel Sauce has its origin in Classic French Cuisine, known as one of the “mother sauces.”