The Difference Between Structure and Cover
Structure and cover, these terms get thrown around so much, newer anglers might get confused as to which is which. I've even heard seasoned anglers use them interchangeably, which makes things even more confusing.
Imagine a smooth aluminum bowl is the lake you're fishing. Turn that bowl upside down and beat on it with a hammer. Any dents, depressions, etc., that you see when you turn the bowl back over could be considered structure. Structure is essentially the land that lies underneath the water. There are scores of structures that all have different names given to them. Points, humps and ditches are a few common ones I'll name.
Cover happens to be whatever is sitting on top of the structure. This could be wood, rocks, grass, etc. With bass fishing at least, finding the structure of the day can make for great fishing.