Final answer:
The DSM-5 specifies that the severity of intellectual disability is determined by both the degree of adaptive functioning and the individual's intelligence test score, considering both cognitive abilities and practical skills.
Step-by-step explanation:
The difference in severity of intellectual disability, as defined by the DSM-5, is specified by both the degree of adaptive functioning and the score on an intelligence test.
In the DSM-5, the degree of one's adaptive functioning, which includes social and practical skills, and the score from an intelligence test are critical components used to assess the severity of an intellectual disability (ID). The term intellectual disability encompasses a range of subtypes including mild, moderate, severe, and profound, which are evaluated based on both intelligence quotient (IQ) scores (typically falling two standard deviations below the mean, around or below a score of 70) and significant limitations in adaptive behavior. This assessment must be consistent with deficits in adaptive functioning that appear before the age of 18. It is important to note that these criteria reflect both the individual's cognitive capacity and their ability to adapt to environmental demands and daily life tasks.