A: Closures and frontals are two different things but they both serve the same purpose-to close off a weave install or a wig.
They both eliminate the need of having to leave your natural hair out to blend with the extensions.
Lace frontals are bigger and wider; they run ear to ear covering your entire hairline at the front. Lace closures are smaller and they primarily close off the horsehoe or "u-part" portion of an install.
Lace frontals are more versatile because they can be parted anywhere ear to ear and lace closures can only be middle or side parted.
They can both be sewn on or glued on. Either a frontal or closure will close off your install and make it look more natural