This is a question that has puzzled many people for a long time. In short, the answer is no – shonen and seinen are not the same thing. Seinen typically refers to stories with a more serious tone, while shonen typically refers to stories with a “lighthearted” tone.
While there are some similarities, shonen and seinen are ultimately two different genres of fiction. If you’re looking for a story that falls into one of these categories, be sure to choose the right one.