What is the difference between upper and lower dentures?

The main difference between upper and lower dentures is, obviously, where they're placed. If a person is missing all of their teeth in both jaws, both upper and lower dentures will be required. However, if a person is missing teeth only on their upper jaw or only on their lower jaw, they may only require one or the other set of dentures. Each denture is custom-made to fit a person's gums and bones, so just as people's upper and lower natural teeth look different, their upper and lower dentures will also look different.