Freelancers are people in game who act like a little wider version of mercenaries, being willing to ship, guard, attack and generally service other factions for credits. They would be classed as civilians and denied access to military ships (which is not the point of Harlequinn's RP, which has her character as a senior Kusari official) for obvious reasons, unless they, like Trent, were working part time for groups like the LSF.
Freelancers make up only a small percentage of the server population. The majority are members of NPC factions. Therefore, an independent/=/freelancer. In most cases, an independent would be the equivalent of a Mafia man who didn't work for any one family. In the houses cases, they are an act of RP cognitive dissonance, save when under the overall authority of the leader of the House Military faction.