Yeah a lot of people don't understand this distinction. You have your pure SWEs who were hired that way who then were either picked for or switched to SRE-SWE. Then you have people who were recruited into SRE-SWE from the beginning. People in SWE and SRE-SWE job classes can freely move between them. Then finally you have people who were recruited as SRE-SysEng, or were recruited as SWEs and didn't quite make the cut. These folks have to do a transfer interview to jump to the SWE or SRE-SWE roles.