This study aimed to distinguish between Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) using magnetic resonance imaging (MRI) and biological analysis in southern Algeria. The study adopted a comparative clinical design to analyze four clinical cases (pure ASD, pure ADHD, dual diagnosis, ADHD with autistic traits) and one control case. Results revealed clear differences: ADHD showed reduced caudate nucleus volume with elevated dopamine levels; ASD showed amygdala enlargement with decreased serotonin levels. The multimodal model achieved 100% accuracy in case classification. Despite these promising results, they remain exploratory due to the small sample size (N=5). The study recommends larger samples and standardized imaging protocols before any clinical application.