The primary difference between Aleve and Motrin is that the active ingredient in Aleve is naproxen, while the active ingredient in Motrin is ibuprofen, as stated by WebMD. Both belong to a class of painkillers known as nonsteroidal anti-inflammatory drugs (NSAIDS) and work in similar ways.
Naproxen and ibuprofen reduce the amount of hormones in the body that are responsible for causing inflammation and pain. Pills containing naproxen, such as Aleve, have a lower risk of contributing to a stroke or heart attack than those that contain ibuprofen or other ingredients. Aleve and Motrin are available in different forms and have unique recommended dosages.