Korg has better organs and punchier drums.Yamaha wins hands down in acoustic instruments especially woodwinds and gtrs.

Yamaha 's style programming is more well mixed where Korg emphasizes in bass/drums.

Hardware/built quality/stylish appearance /compact and low footprint - korg
Smoothness in styles/better RH sounds(Dnc doesn't come close to SA )and ofcourse better 3rd party style support - Yamaha ( even though it's bulky,less compact ,not as good VH compared to Korg.