Children with autism spectrum disorder (ASD) and specific language impairment (SLI) exhibit serious social-emotional difficulties from early infancy which hamper the differential diagnosis of these two conditions. This review aims at analysing differences between ASD and SLI disorders in children from 0 to 12 years regarding emotional competence abilities using eye tracking methodology. The findings show specific markers in the ASD population (e.g. difficulties in facial emotion recognition, atypical visual scanning patterns, or non-social attentional orientation) and a notable scarcity of studies involving SLI children. Comparative research points at potential differences in visual scanning patterns. The conclusions support the use of this methodology for comparative studies between clinical populations.