Many previous studies reported that autistic children have fewer social connections. Yet, recent studies also show that autistic children more often feel lonely in school than allistic (i.e. non-autistic) children. This outcome seems to go against the traditional view that autistic children do not desire to have social connections. Therefore, this study aimed to find out how autistic and allistic children feel about their social connections. We included 47 autistic and 52 neurodiverse-allistic children from two special education primary schools (aged 8-13 years). We tested their social connections and loneliness in school, through a new approach. This new approach includes questionnaires, and sensors for tracking social contacts on playgrounds during school breaks. We found that allistic children felt more loneliness when they spent little time in social contacts during school breaks. Yet, autistic children felt more loneliness when their peers did not like to play with them. For these autistic children, feelings of loneliness may go beyond face-to-face contacts. Being liked as part of a peer group was key. Understanding differences in children's needs can lead to a more effective design for a welcoming school climate.