1. Implementation: Ansible is a configuration management tool used for automating the deployment and management of software applications. It uses a declarative approach, where users define the desired state of the system, and Ansible handles the execution of tasks to achieve that state. On the other hand, Selenium is a testing framework primarily used for automating web browsers. It uses a script-based approach, where users write code to interact with web elements and perform actions.

2. Target Audience: Ansible is mainly targeted towards system administrators and DevOps engineers who manage and deploy software on a large scale. It focuses on infrastructure automation and orchestration. Selenium, on the other hand, is primarily aimed at software testers and developers who need to automate web browser testing. It focuses on functional and regression testing of web applications.

3. Scope of Automation: Ansible is designed for automating tasks related to system configuration, provisioning, and deployment. It can manage a wide range of systems, including servers, networking devices, and cloud resources. Selenium, on the other hand, is specifically designed for automating web browser interactions. It can simulate user actions like clicking buttons, entering text, and validating web page content.

4. Language Support: Ansible uses a YAML-based configuration language, which is easy to read and write for system administrators. It also supports running scripts written in languages like Python and PowerShell. Selenium primarily supports scripting in languages like Java, Python, C#, and Ruby. This allows developers to choose a language they are comfortable with for writing test scripts.

5. Execution Mode: Ansible runs tasks in a push-based model, where the control node sends commands to the target nodes over SSH and executes them remotely. It allows for parallel execution and can manage multiple nodes simultaneously. Selenium, on the other hand, runs tests in a script-based model, where the test code is executed sequentially by controlling the web browser instance.

In Summary, Ansible is a configuration management tool focused on infrastructure automation, while Selenium is a testing framework for web browser automation. Ansible uses a declarative approach, targets system administrators and DevOps engineers, and supports a wide range of systems. Selenium uses a script-based approach, targets software testers and developers, and focuses on automating web browser interactions.