Vyvanse is metabolized differently, so could last longer in your system. It was done so you could not snort it like you can with Adderall. Adderall gives a stronger first "hit". V is smoother and takes longer to take effect so may not be as noticeable. Also the Dose of V should be 30mg compared to 10mgs of adderall XR to be somewhat equal. You might have been under dosed on V
Personally, I'm on Vyvanse at 60mg daily, plus a lunch and dinner dose of methylphenidate at 5mg each. Although I've tried so many different ADD medications and doses before ending up where I am, I agree that Vyvanse does take a while to kick in. Not everyone is the same, so if Adderall works better for you it's not very shocking.
On the drug test aspect, Vyvanse is out of your system exponentially faster than Adderall. The half life of V is 47 minutes compared to a half life of 9-14 hours for Adderall. Example for those unaware how half-lifes of drugs work.
2 subjects; 1 takes 30mg of V, other takes 30mg of Adderall at 12pm. In 47 minutes @ 12:47pm, there will be 15mg (or half original dose) of the parent drug in V user's system. Taking a rough average of Adderall half-life, it would be 12:30AM to reach 15mg of parent drug in Adderall user's system. 1:34pm 7.5mg of parent drug in V user's system (1hr 34mins) where Adderall would be 25 hours to reach 7.5mg in system.
That being said, Vyvanse also leaves metabolites in the system as drug is processed by your body. These are still detectable on drug screens and have a HL of 9-11 hours. Long story short, 2 people, 2 different ADHD medications. Vyvanse is completely out of system and undetectable in urine in 48-60 hours, Adderall completely out of system in 4-7 days.
Personal experience - I take anywhere from 120-200mg of Vyvanse daily. I had negative urinalysis after 48 hours of not taking medication.
Hope that helps...