Whats the difference among adhd.ad and hd only? i think my son had.one of those

Underlying neuro-: Developmental issues in all types of adhd are the same, & related to insufficient available neurochemicals in areas of the brain that sustain attention, inhibit behavior & allow for planning, storage & retrieval of information. Adhd-combined type = significant symptoms of inattention & hyperactivity/impulsivity that started <age 7 & have impaired function at home & school for at least 6 mos.

Its all called ADHD.: Attention hyperactivity disorder (adhd) consists of three subtypes: 1) predominantly inattentive type (the former add); 2) predominantly hyperactive, impulsive type; and 3) combined type. The inattentive type is characterized by poor concentration, being easily distracted, poor organization, can't complete tasks. The hyperactive/impulsive type - fidgets, hyper, blurts out, butts in, etc.