See, the thing is that each different faction equates to a style or theme of play. The company is highly political on one hand and incredibly violent on the other, depending on whether you play the suits or the workers.
The Establishment involves a lot of loyalty and sacrifice from its members and frequently means the members have to do distasteful things that are quite against their nature. Its like a gentleman's club who are occasionally forced to get their hands very very dirty.
The Shop is less straight forward. They generally only take jobs that involve removing bad bad people, corrupt politicians, slave traders, gun runners and the like but they will do terrible things if needs be, but only for the greater good.
As an example, they will accept a job that involves assassinating a trade union leader or revolutionary who is stirring the population to revolt ASSUMING that the military forces of the government are serious enough that any revolt will result in huge civilian casualties. Yes, the leader was a good man with good intentions, but all he was going to achieve was the deaths of his followers. Thus, killing him saves the lives of hundreds, if not thousands who may eventually see their government deposed.
Not a perfect example, but you get the idea.
Black book on the other hand is quite the opposite, no job is too immoral. Some members actively work towards creating strife wherever they can.
The New Crusade is all about service, devotion, fear and paranoia. Their goals are, in their own opinion, altruistic but their attitude is decidely old testament and middle ages. They have decided that the softly softly approach of the new testament has failed abysmally and that more extreme measures are required. As such, almost all members feel that their actions in service of this cause are sufficient to ensure an eternity in hell (lieing, stealing and killing for starters) but they made this sacrifice knowingly.
They can be summed up like so: They have given up their immortal souls to save us from our sins.
I've already done lengthy writeups on the shop, company, establishment and new crusade which I want to review and edit before posting up but they're on the list of stuff I'm planning to post here next week.