Gonna fire this across the port side and see what floats.
Rogues specialize in stealth and cunning. They start with 3 points to allocate between the Subterfuge and Survival skills. They may allocate an additional point to one of these skills every 3 levels (3, 6, 9, 12…). Their Attack Bonus increases by +1 every second level (2, 4, 6, 8…). In combat Rogues can attempt a 'sneak attack' by surprising their enemy (usually subterfuge+DEX bonus, but depends on situation). If this is successful, they can add their Subterfuge skill to the damage of their first attack* or perform an additional attack** with a ranged weapon (if available). Rogues can choose to use DEX instead of STR as the bonus attribute when using light weapons in melee combat.
Savants are characters who have chosen to pursue skills rather than magic or combat. They start with 4 skill points to allocate as they desire. They allocate an additional skill point to any skill every second level (2, 4, 6, 8...). Their Attack Bonus increases by +1 every second level (2, 4, 6, 8…). Savants can be generally good at many things or very good at a few, they can play many different roles from professional scholars to travelling acrobats to scheming vagrants.
*sneak attack would imply the target AC is at -2 for surprise as well...
** the second attack should be against a different target - otherwise it's not really that useful.