Hi Bachus,
Factory Style Format
Korg: 6 cv's for variations ie up to 6 slightly different patterns triggered depending on chord type played. (Most factory styles don't contain 6 cv's but the option is available). Basically adds variety to the variation.

Option of different time signatures in style parts. Again not used in Factory styles, but for songs that may have a 2/4 & 4/4 time signatures in it, One of the variations or fills could be modified to suit. Also be handy if one wanted to create a medley style.

Each of the Korg style parts can be up to 32 bars long including fills. Fills , intro's/Endings if tapped twice will keep looping.

Guitar Mode Tracks. More realistic than midi tracks. Makes recording a simple guitar style track , almost idiot proof. ie Single notes record a variety of strums. Guitar Mode 2 ( PA3X)has the option of also adding midi notes on the same track as Guitar Mode notes.

Second Choice Technics KN7. NTT setting could be set for each individual chord in a stlye track if required. Ability to play some complex patterns.

Yamaha probably has my favourite TYPE of styles, though not my favourite format.

3rd Party styles. Technote. They used to create some wonderful styles for the old Technics Keyboards.