Yes, peaches and nectarines are completely interchangeable in recipes, although nectarines can be a little sweeter so may require less additional sugar then peaches.
Raw and ripe, both peaches and nectarines are perfect for making fruit salads - combined with just one other fruit such as fresh raspberries (with which peaches and nectarines have a natural affinity) or with a mixture of other fruits. Poached in a light sugar syrup, they can be served hot with cream or ice cream, or chilled and used to top a flan or gateau. They can also be spiced, baked, or grilled, cooked with pan-fried ham steaks and pork fillet, or added to casseroles, curries, and stews.
** Asian Recipes