<p>Bali and Lombok are two culturally rich islands in Indonesia known for their distinctive built environments. Despite their proximity, the two-exhibit distinctive architectural features, rooted in different belief systems as physically reflected in their structural configuration. Their traditional and contemporary architectural practices have drawn international historical investigation, design observations, and architectural interpretation, which impact tourism, globalization, and environmental concerns on both islands. Studies on architectural heritage in both regions are required to preserve and develop Indigenous belief systems while contributing to broader discussions on cultural resilience, adaptive design, and the future of Indigenous architecture, not only for these two neighboring islands but also in Southeast Asia. The paper aims to present the cosmological concept for their spatial organization, orientation, and configuration to compare and contrast. By using a combination of a bibliography and a case study, the paper extracts its adherence to cosmological principles and emphasizes communal structures arranged in a hierarchical order using a diagram for qualitative interpretation. Research steps are: (1) Diagram; (2) Extracting cosmological principles; and (3) Comparing and contrasting. The output is the similarity and difference to understand the relationship and uniqueness. The novelty of the research is the cosmological characterization between Bali and Lombok.</p>