Adaptive behavior is paramount for independent living and is varyingly impaired in different neurodevelopmental disorders. This study aimed to investigate differences in adaptive behavior between children with autism spectrum disorder and social communication disorder, two conditions characterized by deficits in social communication. Data from 232 children with autism spectrum disorder and 90 children with social communication disorder were analyzed. Adaptive behavior was assessed using the Vineland Adaptive Behavior Scale--III. Diagnoses were made independently using the Diagnostic and Statistical Manual of Mental Disorders, fifth edition criteria and the AIIMS Modified INCLEN Diagnostic Tool--autism spectrum disorder Diagnostic Evaluation for autism spectrum disorder. Statistical analyses included non-parametric tests and generalized linear models to account for age and sex differences. The results showed that children with social communication disorder exhibited better adaptive behavior than those with autism spectrum disorder across all domains (p < 0.001). The most significant differences were observed in the Vineland Adaptive Behavior Scale-III standard scores in communication (autism spectrum disorder: 50.40 ± 15.51; social communication disorder: 70.53 ± 9.69) and socialization (autism spectrum disorder: 69.46 ± 8.77; social communication disorder: 80.07 ± 6.16) domains. Age and overall adaptive behavior scores correlated well with group membership (p < 0.001). These findings emphasize the importance of distinguishing between autism spectrum disorder and social communication disorder in clinical practice. The results support the use of adaptive behavior assessments in diagnostic evaluations, highlighting the need for tailored interventions.