While Agile, CI/CD, and DevOps are different, they support one another. Agile focuses on the development process, CI/CD on practices, and DevOps on culture.
There are no real differences except the levels at which each term operates.
Agile is a large framework that encompasses the other two practices. It is a philosophy of software development that is implemented in various methodologies – Scrum, Kanban, Scaled Agile Framework (SAFe), etc.
CI/CD is a DevOps tactic, which makes use of the right automated testing tools to implement agile development.
DevOps is an agile development practice and mindset that uses agile principles (collaboration, communication, utilizing the right tools) to streamline software building, testing, and release.
Agile is focused on removing process barriers and enabling the key stakeholders, folk like developers and customers, to collaborate more closely on accelerating delivery. Agile highlights the constancy of change and acknowledges that as software producers, we don’t often know everything we need to successfully conceive, develop, and deliver high-quality software CI/CD is a collection of operating principles and practices that help development teams to deliver frequent code changes reliably. It is the ongoing automation and monitoring throughout the application life cycle - from integration and testing to product delivery and deployment phases.
DevOps is a collaborative culture with a set of practices, ideas, tools, technologies, and processes that streamline the product development process. This huge cultural shift lays emphasis on effective communication, integration, and better collaboration among teams for delivering quality products. Basically, DevOps is a methodology that helps organisations build software - and their production teams - in a way that enables continuous rapid deployment.