1. Runtime environment: Apache OpenWhisk provides a fully managed runtime environment where developers can write functions using various programming languages, such as Python, Node.js, and Java. On the other hand, OpenFaaS allows developers to use any container image as a function, which gives them more flexibility in choosing their preferred runtime environment.

2. Architecture: While both OpenWhisk and OpenFaaS follow the serverless architecture principles, they have different underlying architectures. OpenWhisk follows a microservices-based architecture, where each component runs as a separate service. In contrast, OpenFaaS follows a simpler and more lightweight architecture, utilizing a single container orchestrator.

3. Community support: Apache OpenWhisk is an open-source project supported by the Apache Software Foundation, which means it benefits from a large and active community of contributors. OpenFaaS, on the other hand, is also open-source but has a smaller community compared to OpenWhisk. The size of the community can impact the availability of community-built plugins, support, and documentation.

4. Integration and ecosystem: OpenWhisk provides built-in integrations with popular services and platforms, such as IBM Cloud, and has a rich ecosystem with many available plugins and tools. OpenFaaS, while also offering some integrations, has a more limited set of integrations compared to OpenWhisk. The available integrations and ecosystem can affect the ease of integration with other services and tools.

5. Scalability and performance: OpenWhisk is designed to handle massive scale and can scale up and down to meet the demands of applications with high traffic and workload. It leverages container orchestration technologies like Kubernetes. OpenFaaS, although it can also scale horizontally, may not offer the same level of scalability and performance as OpenWhisk, especially for large-scale applications.

6. Management and monitoring: OpenWhisk provides a robust management and monitoring interface that allows users to track the execution of functions, monitor resource utilization, and manage access control. OpenFaaS, while offering some management and monitoring capabilities, may not provide the same level of granularity and control as OpenWhisk.

In Summary, Apache OpenWhisk and OpenFaaS differ in their runtime environment, architecture, community support, integration ecosystem, scalability and performance, and management and monitoring capabilities. Choose OpenWhisk for a fully managed runtime environment, rich ecosystem, and high scalability, while OpenFaaS offers more flexibility in runtime choices and a simpler architecture.