Methylphenidate, abbreviated MP or MPH, sold under the trade name Ritalin among others, is a stimulant medication used to treat attention deficit hyperactivity disorder and narcolepsy. It is a first line medication for ADHD. Wikipedia
Vyvanse (lisdexamfetamine) is an amphetamine stimulant. Researchers don't know exactly how it works for ADHD, but it increases the activity of the hormones norepinephrine and dopamine in the brain, which improves attention and changes behavior.