Recent numerical and experimental works have shown that both volume-confined hyperbolic polaritons (v-HPs) and surface-confined hyperbolic polaritons (s-HPs) can be excited in hyperbolic materials. However, the study of v-HPs and s-HPs in ultrathin hyperbolic sheets remains elusive. In this work, we show that the traditional methods, such as dispersion relation and distribution of electric field, are not able to identify the different types of HPs in ultrathin hyperbolic sheets. In consideration of the dispersion relation and distribution of electric field, this work indicates that v-HPs and s-HPs can be treated as the same HPs in ultrathin hyperbolic sheets. The electromagnetic waves in the hyperbolic materials are propagating waves and evanescent waves for v-HPs and s-HPs, respectively. Thus, the types of electromagnetic waves in hyperbolic sheets are the only method to identify the types of HPs. We believe that this work will deepen our understanding of the v-HPs and s-HPs, especially in ultrathin hyperbolic sheets.