Canned yams vs. fresh
In preparation, there shouldn't be differences beyond the obvious (cook the fresh, drain the canned, etc), but the flavor will be different. Canned yams are frequently packed in syrup, which will make them very sweet. Some people think that canned goods taste "like can" as well. On the other side, the method used to cook the yams will effect the texture and flavor (boiled will have less flavor and be softer than roasted, etc).