State Government
In this Chapter - (a) "district judge" includes various equivalent judicial titles (city civil court judge, additional/joint/assistant district judge, chief judge of a small cause court, chief presidency magistrate, sessions judge, and related roles); (b) "judicial service" means a service consisting exclusively of persons meant to fill district-judge and other civil judicial posts below that rank.
This is a technical definitions provision, clarifying that "district judge" in this chapter is a broad functional term covering several different specific judicial titles used across different states and court systems, not just one narrow job title.
This is why the constitutional protections in this chapter (like High Court control over postings and promotions) apply consistently to district-level judges regardless of the specific historical title ("sessions judge", "chief presidency magistrate", etc.) a particular state or court system uses for that role.