You can take a different career start for a marginal change in the beginning, .
If I understand correctly, you are saying that the "prelude" part of the game isn't really that different between Corpo, Street Kid and Nomad?
I played two starts, as Corpo and as Nomad.
You start either as Arasaka Counter-Intel employee or as Nomad in the Badlands. As Corpo you get busted trying to betray your boss-boss, fired and Jackie saves you from getting flatlined ... As Nomad you are doing a smuggling job with Jackie that brings you to NC.
After both you get the same or similar to make no difference cutscene covering the next months that establishes you as Merc Team with Jackie, and drops you at the mission to rescue the lady in the bathtub. From there on it's all the same with the occasional special chat option depending on the start that you picked. While these obviously reflect your starting background, and I always tried to pick that option to continue, they don't really seem to alter the flow of the story.
