My impression is that Linux tries to give sysadmins tools to secure existing binaries with containers, secomp, syscall filters etc. OpenBSD focuses on securing

My impression is that Linux tries to give sysadmins tools to secure existing binaries with containers, secomp, syscall filters etc. OpenBSD focuses on securing things at the source level. Hence all the compiler tricks to mitigate memory safety bugs, API for programmers to limit syscall exposure, privilege separation within individual programs, drive to avoid unnecessary complexity so the source is readable etc.