Because pool covers actually cover the surface of the pool, they are much safer than the fences. A child or dog could get over the fence and still get in the pool. The covers for in-ground pools are stretch tight across the surface of the pool and anchored in the deck. These are not removable by kids and can hold incredible weights. For the above-ground pools, those are tight as well and not easily manipulated by children. These complete items make covers safer than fences in regard to kids and pets getting in the pool unexpectedly.