Here's the deal, Dexedrine is pure dextroamphetamine(d-amp), and vvyanse is l-lisdexamphetamine aka it's a pro-drug of d-amp. The only way vyyanse is effective is when taken orally as it has to be metabolized into dextroamphetamine as the lucein chain is knocked off through gastro-intestinal enzymes. So in short, Vyyanse is dextroamphetamine with lucein attached to it to render it useless if taken any other route of administration other than ORAL. Think of Vyyanse as an extended-extended release dexedrine... I prefer dextroamphetamine sulphate tablets over all other forms of amphetamine.
As to comparing to Adderall, adderall is about 75% or so dextroamphetamine and the rest is levoamphetamine... Dexedrine is much smoother with quite less PNS side effects... It's more recreational. Levoamphetamine(L-AMP) is not really wanted unless you really wanna get a kick in the ass.