Linux: You can't fork Linux!!!!!!
BSD: So uh this shit originally ran on a PDP with a 11-1/2 bit wordsize then it got forked in to AIX, Ultrix, Tru64, DYNIX, SunOS, DomainOS, JunosOS, CellOS, pfSense, the Playstation, Nintendos, and now it just spawns on its own.