1. Traffic Management: The key difference between Istio and Kiali is that Istio focuses on traffic management, providing features like load balancing, routing, and traffic splitting, while Kiali focuses more on observability and monitoring of the services within the mesh.
2. Service Visualization: Istio offers service visualization capabilities, allowing users to see how services are connected and communicate within the mesh, while Kiali provides detailed visualizations of service dependencies, traffic flow, and performance metrics, enabling users to better understand the relationships between different services.
3. Security Features: Istio offers robust security features such as mTLS (mutual Transport Layer Security) for secure communication between services, while Kiali does not provide specific security features and focuses more on monitoring and visualization aspects.
4. Policy Enforcement: Istio enables the implementation of policies for access control, rate limiting, and authentication at the service level, whereas Kiali does not have native policy enforcement capabilities and mainly focuses on monitoring and visualization.
5. Integration with Prometheus and Grafana: Istio seamlessly integrates with monitoring tools like Prometheus and Grafana for collecting metrics and creating dashboards, while Kiali works well with Istio to provide enhanced visibility but does not offer direct integrations with these monitoring tools.
6. Control Plane Functionality: Istio includes its control plane components for managing traffic, policies, and security within the mesh, while Kiali relies on Istio's control plane for data collection and visualization but does not have its control plane functionality.

In Summary, Istio primarily focuses on traffic management, security, and policy enforcement within the service mesh, while Kiali specializes in service visualization, monitoring, and observability features.