Most of these professions are fairly straightforward; Harvesters harvest crafting materials, Armortechs and Weapontechs craft armor and weaponry, Biotechs craft biological augmentations to enhance players' abilities, Chemists create "powerful enhancements that can turn the tide of any battle," and Inventors appear to invent new schematics that other crafters on their faction can use to create new and more powerful items.
But what about the black sheep of the bunch, the Soldier for Hire? That's where things get interesting. Perhaps you're the sort of player that would rather make a living destroying things than creating them. If so, the Soldier for Hire is right up your alley. You work as a mercenary, protecting other players, with your payment worked right into the game mechanics. The full details on the rather in-depth crafting system can be found on the game's official site.