I've recently purchased the ping g15 driver and was curious to find out the difference between the G15 line versus the ping k15 driver. Since I bought my Pings from Mygolfwholesale, I always have the option of trading it at 10% loss. That being said, what I've found out will most likely make me keep my G15's and pass on the K15's. For the driver, here are some of the differences

Ping K15 Driver

The ping k15 has an elongated head design that combines with an external weight pad to position the center of gravity for higher launching and longer carry drives. It is engineered with Straight Flight Technology (SFT) which promotes natural club head rotation by concentrating approximately 10% of the head mass towards the heel. A larger face increases forgiveness and ball velocity for greater distance and accuracy.

PING G15 Driver

The ping g15 is engineered for golfers seeking a maximum forgiveness driver that delivers distance and accuracy. Its 460cc titanium head is longer front to back and features PING's patented ultra thin crown technology. Weight savings from the thin crown are positioned as an external sole weight to optimize the center of gravity for higher trajectories and reduced spin. A larger face is designed to increase ball speed and provide consistency across the entire hitting surface. The new PING-designed TFC 149D high balance point shaft allows for a five gram increase in head mass (without increasing swingweight or overall weight) which results in higher ball speeds and an increased moment of inertia.

It appears the K15 is indeed a replacement for the Super Game improvement Rapture line. That being said, the design and color appears to be closer to the G15 than the old Rapture.