Okay.
Adderall is what is known as racemic amphetamine sulfate, and contains both parts (isomers) of the amphetamine molecyle.
75 % Dextro and 25 % Levo if Im not mistaken.
The dextro isomer is known to be more stimulating on the mind while Levo is more stimulating in a physical way, which for some, means more side effects due to its effects on the peripheral nervous system, which is why a lot of people prefer the pure dextro isomer, known as dextroamphetamine. You will easily find people who prefer Adderall over dex also though.
Vyvanse is the brand name for the drug Lisdexamphetamine, and this is not active in its orginal form, its what is known as a "prodrug".
When consumed, your body metabolizes the drug, making it into dextroamphetamine, which is very much active.
The reason why they have made this prodrug, when dex is already on the market, is because the abuse potential is very low when compared to dex IR tablets. After ingestion, the effects wont become apparent until enough lisdexamp has been metabolized in order for you to feel its effects and the duration of action is also longer than what is the case for dexamp.
You can think of it as being a dexamp extended realease tablet.
What would be the best option for you is hard to say, as everyone is different. If your planning on being on the drug for as long time during the day as possible, when I would point you towards lisdexamp.
If you are planning on using more as an "as needed" thing, when Adderall would be a good place to start as it starts to work fast and the duration is shorter than lisdexamp.
The very best thing would be to try both drugs, and also dexamp if your doc is willing to prescribe it. Hell, methylphenidat (ritalin) might be worth a shot too.
You should know though, that most doctors arent that willing to play around with these drugs in order to find the right one at the right dose.
If you were to try lisdexamp and when told your doc that it works but that you would like to try Adderall in order to see if it might be even better, then a lot of docs wouldn´t do it.
What you can do about this if you want to test different drugs before choosing the right one, is saying that it works a little, but that its not enough/you were hoping for more relief.
Then your chances of trying other stuff is good and its easy to go back by saying the other drugs didn´t work as well as the first (or second, third, whatever) so you´ll "take what you can get".
This is what I have done in the past in order to find what works the best for me.
As a side-note, not once has the drug that my doc started with been the one I ended up choosing.
If you haven´t done so already, when you might want to check up on how to treat ADHD without drugs (those things works both with and without drugs!) and also, the do´s and dont´s when taking amphetamine.
You might want to check out stuff like Magnesium as a supplement if your going to take amps often, just to start you of somewhere
Good luck with it sir, ADD/ADHD symptoms is a bitch!