And yes, his age as well as the medications you have tried would help.
Yes, medications are different. They range from stimulant
to non stimulant
. From extended release to ones with a much shorter time span.
It certainly sounds like you should be getting some more information from your doctor. A very good overall coverage of AD/HD (meds, symptoms,behavioral help, etc) is provided by the book, "The ADD/ ADHD Answer book," by Susan Ashley.