This study presents a comparative analysis of the stiffness characteristics of brick masonry based on experimental data and an orthotropic model. The main focus is on the influence of mortar joint strength on the anisotropy of the elastic properties of masonry. For three series of samples (KRO-1, KRO-2, KRO-3) with different mortar strengths, experimental compression tests were conducted, along with numerical modeling in the Abaqus software, including micro-modeling and macro-modeling based on an orthotropic model. The results demonstrate that the ratio of the elastic moduli of brick and mortar (Eb/Em) significantly affects the distribution of strains and stresses in the masonry. An asymmetry in the stiffness matrix (D12≠D21) was observed, indicating the need to account for micromechanical effects in the "brick-mortar" contact zones. The highest anisotropy was found in samples with low-strength mortar (series KRO-3), where the anisotropy coefficient D11/D22 reached 1.253. The study confirms the validity of using an orthotropic model to describe the stiffness characteristics of masonry but highlights the necessity of its modification to account for structural heterogeneity and edge effects. The obtained results have practical significance for the design of masonry structures under complex stress conditions.