Shaped nappies fasten with aplix, snaps or a nappy fastener and are the absorbent part of a two part nappy system as an alternative to a flat nappy (such as a prefold or terry). They need a PUL (polyurethane laminate) wrap or wool cover over the top.
Shaped nappies are the most absorbent and provide the best containment of all the nappy types, and therefore are the best choice for night time, but also work great in the day time.
Flat nappies - prefolds or terry nappies are the original nappy type, which our grandparents probably remember using. A basic rectangle of fabric, which is folded and secured, or simply pad folded and placed in a wrap. These also require a wrap.