Although many fishermen use the terms cover and structure when talking about the same thing, there are differences. If you know the difference between cover and structure it might help you better understand how to fish each, and be able to follow discussions and fishing articles better.
Cover
Cover is anything in the lake a fish can use for hiding. Common types of cover are weeds and water plants, stumps, rocks, blowdowns, cypress or other trees growing in the water and brushpiles. Bass and other fish like pike are ambush fish. They use cover to hide and then grab a prey like a baitfish that comes close to them. Although bass will chase down food in open water, they are made for quick bursts of speed and prefer to dart a short distance to inhale dinner.
Structure
Structure is a feature of the bottom. Common types of structure include points, channels, ledges, drop offs and contour changes. A change in bottom type, for example, from sand to clay, is also structure. Structure is the paths bass use to follow in their migration routes and feeding movements. A creek channel coming out of a cove is structure the bass will follow when they move to shallows to spawn, and also the path they follow when moving into the cove to feed.
If structure is the path the bass follows, cover is the resting and feeding stops along the structure. A stump on the lip of a creek channel offers cover for the bass to stop and ambush prey, or pause on their movement along the structure.
Fish like bass like to hold on cover that is on structure. The stump on the creek channel is a good example. A brush pile out on a point is another good example of cover on structure that will hold bass, as are rocks on points or contour lines.
To catch fish like bass identify the structure and then find cover on it.