1. Prepare grill or heat oven to 425 degrees F.
2. Peel baking and sweet potatoes; cut into 3/4-inch-thick wedges. Toss baking potatoes with 1/2 teaspoon each salt and pepper in large bowl. Coat with cooking spray.
3. Place baking potatoes on sheet of heavy-duty foil or meshed grill rack placed directly on top of grill rack.
4. Grill or roast 20 minutes, turning.
5. Meanwhile, combine sweet potatoes, remaining 1/2 teaspoon each salt and pepper in same bowl. Coat with spray. Add to baking potatoes. Grill or roast 20 minutes longer or until fork-tender.