it depends on what you're doing or stabilizing, interfacing is used for mostly clothes, sometimes bags, but it can be used to stabilize t-shirts when doing a t-shirt quilt, stabilizer is used mostly for embroidery, and appliques where you want to stabilize your stitches so your fabric doesn't pucker. Also there are so many different types, tear away cutaway, wash away, heavyweight, lightweight, you erally need to know what you are working on. they both kind of stabilize, but in different ways. Interfacing adds more body to a fabric, but you can also use fusible interfacing in applique if you want the needle turn look