Can you explain to me ritalin crash compared to vyvanse (lisdexamfetamine) and other adhd medications?

There are only two: stimulants, methylphenidate & Amphetamine. Since 2000, multiple delivery systems of each have been produced. Each differs in onset of action, time of peak clinical effect & duration of action. Longer & more consistent drug delivery gives better symptom control & reduces symptoms of "rebound" ADHD, irritability, emotional lability & the "crash" noted by some teens & adults as the effect wears off