The single-line-to-ground faults with line breaks (SLGFs-LBs) occur more and more frequently in distribution networks and can cause major safety accidents. It is difficult to distinguish the single-line-to-ground faults (SLGFs) in resonant grounding systems and ungrounding systems due to the same electrical characteristics on the source side and uncertain operation conditions of distribution networks. This paper proposes a method for distinguishing SLGFs-LBs and SLGFs. First, the source-side and load-side voltage characteristics of SLGFs and SLGFs-LBs are analyzed, and the phase difference between the voltages of the fault phase and non-fault phase on the load side is selected as the identification criterion. Phasor measurement units (PMUs) are selected as measuring devices. Then, the effects of operation conditions and external devices in distribution networks on the proposed method are discussed, and the phase errors caused by them are calculated to correct the identification method. Finally, the field testing and simulation experiments are conducted to verify the effectiveness and robustness of the proposed method.