Roles are a function of the people you have and the primary responsibilities and functions they perform. They focus on some level of abstraction usually based

Roles are a function of the people you have and the primary responsibilities and functions they perform. They focus on some level of abstraction usually based on their training/background and the overall needs. SREs are coders who know IT system. So they treat IT as code as much as possible. They solve problems by abstracting them into code. Closely related are DevOps who are usually IT who know some coding. Maybe they run development operations, so the infrastructure and tasks needed to keep the developer infrastructure running. They solve problems by scaling known components and applications. Quality Assurance Engineers are testers who can code or perhaps know some systems deeply vs being an application specialist.