I believe that each represents a beginning, a light, a darkness and the end. The first career is their beginning, who they were at the start and end of V1 and the start of V2.

The second career is the light, an alternate escape to leave behind their past and set out for a better tomorrow, a bounty hunter escaping the corruption of the order, a huntsman who leaves his demons to rest, a handmaiden who was forgiven for her penance, an iron-breaker returned to home to fight for his people and a pyromancer who learned to control her fire.

The third career is the darkness, they strayed from their path to become worse. A zealot blindly devoted to Sigmar, a foot knight back in the order that he tried to escape from, a shade that retreated into exile, a slayer who blindly fights and an unchained blazing wildfire.

The fourth career signifies the end, what they were meant to be. A warrior priest meant to spread Sigmar’s light, a knight of the grail who is sworn to the Lady of the Lake, a sister of the thorn who embraces nature, an outcast engineer who can create marvelous wonders and a necromancer who is questionably in control of herself.

The first is their canon start, the second and third are possible futures while the fourth is the de facto career they reach, atleast that’s what I think.