Two burning substation Missions?

From what I can tell there are different station amount requirements for the two. One is a version for those that don't have police stations yet, this is added in to have a variety of calls out there for newer members. Then there is one where it requires a squad car, this was added in to give a fire call for PD to respond to. Obviously I'm not a dev or a moderator but those would be my best guesses.