Perhaps this might help for dose comparisons:
"A 25 mg Vyvanse capsule would be molecularly equivalent to a 10 mg Dexedrine Spansule (both are about 7.425mg dextroamphetamine base), although a 25 mg Vyvanse capsule is not commercially available.[citation needed] However, the molecular equivalence ratio does not mean that the respective doses of Vyvanse and Dexedrine XR (Spansule) are bioequivalent because the two formulations have slightly different pharmacokinetic profiles. For example, while the area under the curve for the aforementioned pharmaceuticals is equivalent, the peak exposure (Cmax) to the active compound dextroamphetamine is about 50% higher for Vyvanse than for Dexedrine XR.[4]"
-Wikipedia
But as for the differences between this and "street" amphetamines; I have found Dextroamphetamine (What Vyvanse turns into) much less tweaker-friendly. I have had friends who have taken like 200mg of d-amphetamine who were extrenmely heavy ice-methamphetamine users and didn't enjoy it as much because they say it didn't force them to do something; ie. re-arrange the garage and then put it back the way it was etc.
Basically:
Pharmaceutical Stimulants: Measurable doses, Less jittery, More mental focus, "less" physical activity pushiness street-amps tend to have,
No cuts in your product!
"Street" Speed: With the non-crystal methyl-amphetamines it is very easy to introduce similar cuts which could be anything from caffeine to pseudophed to lactose, Huge sketch-factor (for me) which is great for dancing I suppose; not so much for home/school-work and daily life's requirements. It is almost impossible to dose street-speed properly unless you know the purity and have a scale with you for dosing; which is impractical. Some dealers stomp their shit hardcore and others may not, even if you do get a good product I find taking too much can actually destroy the ability to use it for ADHD concerns; you all know "that" person who won't shut up about nonsensical jibber-jabber.
But any other questions you want help on you can PM me; or if you are a greenlighter, you can use the AIM icon to grab my screen-name and hit me up there "FlyWithCloudNine"
Adderal contains 4 different preparations of amphetamine, all of which can be seen here:
http://www.medicineonline.com/drugs...ingle-Entity-Amphetamine-Product-Rx-only.html
But it is well known that Adderal is 72% d-amphetamine and 28% l-amphetamine whereas with street-speed you have no way to tell in practicality unless you use two polarized lenses and what amount of the product is the "worthless" (l)levo-isomer, or how much is the (d)dextro-isomer.
Basically levo can't cross the BBB effectively and won't induce euphoria or other mental affects but just force your body to stay awake; there is a reason why I can go spend $4 and get a tube of "L-Methamfetamin" which is just another weird way "Vick's" spelled the chemical. Anyways, street is usually about 1/2-1/2 OI would think? Unless you have a source who would isolate it? I can imagine no reason to isolate the l,d isomers unless its for personal consumption because l-amphetamine itself would make a great cut anyways...