The key feature that distinguishes a public cloud from a private cloud is the level of accessibility. A public cloud is a shared environment where resources and services are made available to multiple organizations via the Internet, typically at a lower cost. In contrast, a private cloud is dedicated to a single organization, providing more control, security, and customization options. While public clouds offer scalability and cost-efficiency, private clouds prioritize privacy and compliance, making them suitable for sensitive enterprise data and workloads.