The majority of the research examining children with Autism Spectrum Disorder (ASD) and Williams Syndrome (WS) focus on the social domain while few have examined cognitive style and emotionality. Accordingly, this current study assessed the day-to-day cognitive and behavioral functioning of school-age children with ASD, WS, and neurotypical development (ND) through caregiver-report inventories to further delineate commonalities and disparities in cognitive and social-emotional traits. Two caregiver-report inventories, the Children's Behavior Questionnaire and the Multidimensional Personality Questionnaire were employed to assess the day-to-day functioning of children ages 7-14 years. Participants included 64 caregivers of children, of these, 25 were caregivers of children with high functioning autism (HFA), 14 with WS, and 25 with ND. Multivariate analysis of covariance was computed to assess between-group differences for each subscale within a questionnaire. Covariates included age and full-scale IQ. For cognitive traits, group differences were observed across two categories while seven were present within the social-emotional categories. The majority of the group effects reflected differences in social-emotional traits between ND and both neurodevelopmental groups, while limited distinctions were found between the two clinical groups. This brief report provides additional evidence that HFA and WS may show similarities in cognitive traits but more divergent social-emotional tendencies, despite controlling for age and intellect. This study highlights the large social-emotional differences that supports prior phenotypic descriptions of both neurodevelopmental groups. Future research in these domains are needed to determine focused interventions to address social impairment.