Modafinil is a psychostimulant that treats sleep disorders such as narcolepsy, sleep apnea, or shift work sleep disorder. Moreover, it helps improve cognition, fatigue, and mood disorders.
On the other hand, Vyvanse is a psychomotor stimulant that is advised to treat Attention Deficit Hyperactivity Disorder (ADHD).
Both Modafinil and Vyvanse are category pregnancy drugs; therefore, their use during pregnancy and breastfeeding must be under consultation. Moreover, they are FDA-approved medicines and both act in the central nervous system to produce their effect.
The comparative study of Modafinil vs. Vyvanse states that Modafinil is an effective and safer option to treat sleep disorders, cognition, fatigue, and mood swings. While Vyvanse is a better option to treat the signs of ADHD.
Read more about Modafinil vs. Vyvanse.