An analysis of molecular single-phase distributions inside slitlike and cylindrical pores with homogeneous walls was carried out in a wide range of pressures and temperatures, when there is liquid or vapor in it. The pore walls are considered nondeformable; they form an external field for the fluid. The state of the "liquid in a pore" and "vapor in a pore" phases satisfies the equality of the chemical potential with the chemical potential of the bulk phase. The molecular distributions were calculated within the framework of the lattice gas model (LGM) with the simplest pair interaction potential of nearest neighbors. The distribution of molecular density in the inhomogeneous field of pore walls is associated with local distributions of two types of pressure: isothermal, associated with the chemical potential of the system, and internal mechanical pressure (or expansion pressure in terms of the LGM). The difference between each of the two types of pressure with the corresponding pressure in the bulk phase determines the disjoining pressure, which is actively used in the thermodynamic interpretation of the characteristics of thin layers depending on their width. It was found that both types of disjoining pressures in slitlike and cylindrical pores are proportional to each other. The proportionality coefficient depends on the parameter of the adsorbent–adsorbate interaction potential and its extent, pore geometry, and temperature, and also depends on the width of the cylindrical pores, but does not depend on the width of the slitlike pores. The dimensional derivatives of the two types of disjoining pressure from the pore width, through which the adsorbate flows are expressed, are also related to each other by the same proportionality coefficients. [ABSTRACT FROM AUTHOR]