What is the difference between add and adhd in boys?

Very very close: Add - attention deficit disorder adhd - attention deficit hyperactivity disorder the hyperactivity part is due to the inattention and due to the poor focus. So mechanism is same for both, treatment is same.

Rose by another name: Add and adhd are often used interchangeably - we used to refer to adhd with or without hyperactivity and now the nomenclature is adhd either predominantly inattentive type, predominantly hyperactive/impulsive type, combined type or other. Adhd inattentive type is more often associated with slow processing speed, depression, and anxiety.