A scrum team is a closed GROUP consisting of the Scrum Master, the Product Owner, and the team. All three entities in the scrum team are aligned towards a single goal. In the scrum team, the scrum master will make sure that the team is focused and will PROTECT the sprint from outer interferences. On the other HAND, the product owner will align the prioritized requirements, so that the team has a lined up stories to work on. And the third entity in the Scrum Team is the development team who is focused on the delivery of the value to the stakeholder. 

The development team takes up the ‘actual work’ in terms of coding, testing, etc. As per the scrum.org “Development Team consists of professionals who do the work of delivering a potentially releasable Increment of “Done” product at the end of each Sprint. A "Done" increment is required at the Sprint Review. Only members of the Development Team create the Increment.” The development TEAMS are self-organizing and cross-functional, no one directs the Development Team how to turn Product Backlog into Increments of potentially releasable functionality. Specific Development Team members may have specific skills and areas of focus, but accountability lies to the Development Team as a WHOLE.