The presence of carbonate groups along the polymer backbone of polyether carbonate polyols leads to distinctly different physicochemical properties compared to structurally related polyether polyols. For instance, polyether carbonate polyols are characterized by their substantially higher viscosity. Targeting at understanding the underlying reasons for the different properties, we carried out detailed diffusion and viscosity studies on a series of diols with molecular weights in the oligomer range. We found that conventional polyether diols are subject to few topological constraints and show classic diffusiveness over a broad molecular weight range. In comparison, polyether carbonate diols exhibit much stronger topological constraints and form temporarily fixed networks on the same time scale. This results in time dependent diffusion coefficients, a distinctive phenomenon, which is analogous to subdiffusion in porous media. Accordingly, the dynamics of polyether carbonate diols in melt is very different from the dynamics of polyether diols. Such detailed understanding of the properties of polyols, which are widely used bulk chemicals in polyurethane manufacture, seems essential for introducing CO2-derived polyether carbonate polyols as sustainable building blocks for well-defined polyurethane materials.