Background Prolonged grief disorder (PGD) is newly included in the text revision of the DSM-5 (DSM-5-TR). So far, it is unknown if DSM-5-TR PGD is distinguishable from bereavement-related posttraumatic stress disorder (PTSD). Prior research examining the distinctiveness of PTSD and pathological grief focused on non-traumatic loss samples, used outdated conceptualizations of grief disorders, and has provided mixed results. Objective In a large sample of traumatically bereaved people, we first evaluated the factor structure of PTSD and PGD separately and then evaluated the factor structure when combining PTSD and PGD symptoms to examine the distinctiveness between the two syndromes. Methods Self-reported data were used from 468 people bereaved due to the MH17 plane disaster ( N = 200) or a traffic accident ( N = 268). The 10 DSM-5-TR PGD symptoms were assessed with the Traumatic Grief Inventory-Self Report Plus (TGI-SR+). The 20-item Posttraumatic Stress Disorder Checklist for DSM-5 (PCL-5) was used to tap PTSD symptoms. Confirmatory factor analyses were conducted. Results For PTSD, a seven factor, so-called ‘Hybrid’ model yielded the best fit. For PGD, a univariate factor model fits the data well. A combined model with PGD items loading on one factor and PTSD items on seven factors (associations between PGD and PTSD subscales r ≥ .50 and ≤.71), plus a higher-order factor (i.e. PTSD factors on a higher-order PTSD factor) (association between higher-order PTSD factor and PGD factor r = .82) exhibited a better fit than a model with all PGD and PTSD symptom loading on a single factor or two factors (i.e. one for PGD and one for PTSD). Conclusions This is the first study examining the factor structure of DSM-5-TR PGD and DSM-5 PTSD in people confronted with a traumatic loss. The findings provide support that PGD constitutes a syndrome distinguishable from, yet related with, PTSD.