The COVID-19 pandemic prompted unprecedented global efforts in vaccine development. Among the prominent platforms, mRNA vaccines (e.g., Pfizer-BioNTech, Moderna) and viral vector vaccines (e.g., AstraZeneca, Johnson & Johnson) were developed at record speed. This article offers a comprehensive comparative analysis of these two technologies, examining their mechanisms, efficacy, safety profiles, storage requirements, global distribution, and public perception. It further expands on immunological responses, policy implications, and lessons for future pandemic preparedness. The article aims to present a scientific yet accessible synthesis of current evidence to inform public health strategies and research priorities.