In this work the detailed geometrical description of all possible orthogonal and nonorthogonal systems of coordinates, which allow separation of variables of two-dimensional Helmholtz equation is given as for two-sheeted (upper sheet) H2, either for one-sheetedH2 hyperboloids. It was proven that only five types of orthogonal systems of coordinates, namely: pseudo-spherical, equidistant, horiciclic, elliptic-parabolic and elliptic system cover one-sheetedH2 hyperboloid completely. For other systems onH2 hyperboloid, well defined Inönü-Wigner contraction into pseudo-euclidean plane E1,1 does not exist. Nevertheless, we have found the relation between all nine orthogonal and three nonorthogonal separable systems of coordinates on the one-sheeted hyperboloid and eight orthogonal plus three nonorthogonal ones on pseudo-euclidean plane E1,1. We could not identify the counterpart of parabolic coordinate of type II on E1,1 among the nine separable coordinates on hyperboloidH2, but we have defined one possible candidate having such a property in the contraction limit. In the light of contraction limit we have understood the origin of the existence of an additional invariant operator which does not correspond to any separation system of coordinates for the Helmholtz equation on pseudo-euclidean plane E1,1.Finally we have reexamine all contraction limits from the nine separable systems on two-sheeted H2 hyperboloid to Euclidean plane E2 and found out some previously unreported transitions.