Is Vyvanse basically the same as meth? What actually differs between amphetamine and methamphetamine chemically.

Not really, and this comparison misunderstands basic chemistry. Amphetamine and methamphetamine are related molecules, but they differ in a single methyl group that changes how the drug crosses into the brain and how strong its effects are; prescribed amphetamine salts like those in Vyvanse are dosed, regulated, and metabolized very differently than illicit methamphetamine. Vyvanse specifically is a prodrug, lisdexamfetamine, meaning it's inactive until enzymes in the body slowly convert it to active dexamfetamine, which blunts the rapid high associated with misuse and is part of why it's classified with a lower relative abuse potential than immediate-release stimulants. If the change is persistent, distressing, or affecting daily functioning, contact your provider through the FasTreat portal rather than changing medication on your own. References: https://health-products.canada.ca/dpd-bdpp/index-eng.jsp

Had a coworker say this to my face once, completely serious. I just started explaining the prodrug thing and watched their eyes glaze over, but at least they stopped saying it after that. Now I just correct people matter-of-factly instead of getting defensive about it, since the confusion usually comes from not knowing the chemistry rather than any real hostility.