The three functional levels of autism:
Level 1: Requiring Support: Problems with inflexibility, poor organization, planning, switching between activities, which impair independence. Poor social skills, difficulty in initiating interactions, attempts to make friends are odd and unsuccessful.
Level 2: Requiring Substantial Support: Marked difficulties in verbal and nonverbal social communication skills. Markedly odd, restricted repetitive behaviors, noticeable difficulties changing activities or focus.
Level 3: Requiring Very Substantial Support: Severe difficulties in verbal and nonverbal communication. Very limited speech, odd, repetitive behavior; many express their basic needs only.
https://www.verywellhealth.com/what-are-the-three-levels-of-autism-260233