The most obvious difference between Lace Frontals and Lace Closures are the size. Lace Frontals are larger, because they are designed lay temple to temple providing coverage for the entire hairline. Lace Closures are smaller as their primary purpose is to close off an install, hence the name closure. Closures typically only cover a horseshoe size portion at the top or front of an install, commonly referred to as "leave out".
Depending on your style of choice, a Lace frontal may be more appealing than a closure or vice versa. If you like to pull your hair back then a lace frontal will be best for you. Whereas, if you simply want to close your install with a natural looking scalp then a lace closure will be the best solution for you. Either way they both will enhance your install by giving it the sought after "natural look" that we all go for!