The difference is the amount of the 2 active ingredients.
Vicodin contains 5 mg of Hydrocodone and 500 mg of acetaminophen (tylenol)
Lorcet+ contains 7.5 mg of Hydrocodone and 750 mg of APAP (the abbreviation for acetaminophen)
So the Lorcet+ is the stronger of the 2, because there's more hydrocodone in it.
THe half life of hydrocodone is 4 hours depending on several factors (weight ,age, metabolism ,and usage amount are several factors). One single dose can have a detection on a urine sample for up to 5 days.
Source of material:
Erowid Drug Testing Vaults : The Basics Hydrocodone - Wikipedia, the free encyclopedia Hydrocodone Hydrocodone Bitartrate And Acetaminophen Tablets